Touch detection device, touch detection method and touch screen panel, using driving back phenomenon, and display device with built-in touch screen panel

ABSTRACT

Provided is a touch detection device, touch detection method, and touch screen panel, which detects a touch signal by detecting a driving back phenomenon occurring in a touch pad by a driving voltage applied to a driving capacitor, and a display device with a built-in touch screen panel. The touch detection device that is added on top of a display device and detects occurrence of a touch capacitance (Ct) by an approach of a bodily finger ( 25 ) or a touch input instrument such as a conductor similar to the bodily finger, the touch detection device comprising: a touch pad ( 10 ) that forms the touch capacitance (Ct) between the touch input instrument and the touch pad; a driving capacitor (Cdrv) whose one side is connected to the touch pad ( 10 ) and to the other side of which a driving voltage for detection of a touch input is applied; a common voltage detector that detects a common voltage generated from the display device; a driving voltage generator that generates the driving voltage in synchronization with the common voltage; and a touch detector that is connected to the touch pad ( 10 ), and that detects a touch signal by using a driving back phenomenon when the touch capacitance (Ct) is added to the driving capacitor (Cdrv) according to occurrence or non-occurrence of a touch in the touch input instrument. A touch signal is detected while avoiding a point in time of a change of a common voltage state, and a driving voltage is applied through a driving capacitor connected to a touch detector, to thus detect whether or not a driving back phenomenon occurs in the touch detector and to thereby acquire a touch signal. Accordingly, an influence due to parasitic capacitance generated by noise, coupling phenomenon or other factors is minimized, to thus acquire a touch signal stably.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/347,892 filed Mar. 27, 2014 (now pending), which is a national entryof International Application No. PCT/KR2012/007940, filed Sep. 28, 2012,which claims priority to Korea Patent Appl. No. 10-2011-0098749 filed onSep. 29, 2011 in the Korean Intellectual Property Office, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a device, method, and touch screenpanel, for detecting a touch input of a bodily finger or a touch inputinstrument having conductive characteristics similar to the bodilyfinger, and a display device with a built-in touch screen panel, andmore particularly, to a touch detection device, touch detection method,and touch screen panel, which acquires a touch signal by using a drivingback phenomenon occurring in a touch detector when a driving voltage isapplied to a driving capacitor connected to the touch detector, and atouch input occurs, and a display device with a built-in touch screenpanel.

BACKGROUND ART

Usually, touch screen panels are input devices which are respectivelyattached onto display devices such as LCDs (Liquid Crystal Displays),PDPs (Plasma Display Panels), OLED (Organic Light Emitting Diode)displays, and AMOLED (Active Matrix Organic Light Emitting Diode)displays, to thus generate an input signal corresponding to a positionwhere an object such as a finger or a touch pen is touched on the touchscreen panel. The touch screen panels are widely used in various fieldsof mobile devices such as small-sized portable mobile phones, industrialterminal devices, and DIDs (Digital Information Devices).

Various types of conventional touch screen panels are disclosed, butresistive type touch screen panels having simple manufacturing processesand inexpensive manufacturing costs have been used most widely. Theresistive type touch screen panels, however, have a low transmittanceand undergo a pressure to be applied, respectively, to thereby cause aninconvenient use. The resistive type touch screen panels also havedifficulties in recognizing multiple touches and gestures, and causedetection errors.

In contrast, capacitive touch screen panels may have a hightransmittance, recognize soft touches, and recognize multiple touchesand gestures satisfactorily, to thus widen a market share gradually.

FIG. 1 shows an example of the structure of a conventional capacitivetouch screen panel. Referring to FIG. 1, in the conventional capacitivetouch screen panel, transparent conductive films are respectively formedon the top and bottom surfaces of a transparent substrate 2 made ofplastic or glass. Metal electrodes 4 for applying a voltage are formedat each of four corners of the transparent substrate 2. The transparentconductive film is formed of transparent metal such as ITO (Indium TinOxide) or ATO (Antimony Tin Oxide). The metal electrodes 4 respectivelyformed at the four corners of the transparent conductive film are formedby printing low resistivity conductive metal such as silver (Ag). Aresistor network is formed around the metal electrodes 4. The resistornetwork is formed in a linearization pattern in order to transmit acontrol signal equally on the entire surface of the transparentconductive film. A protective film is coated on top of the transparentconductive film including the metal electrodes 4.

In the case of the capacitive touch screen panel, when a high-frequencyalternating-current (AC) voltage is applied to the metal electrodes 4,the high-frequency alternating-current (AC) voltage is spread to thewhole surface of the transparent substrate 2. Here, if a finger 8 or aconductive touch input unit lightly touches the top surface of thetransparent conductive film on the transparent substrate 2, a certainamount of electric current is absorbed into the human body and a changein the electric current is detected by a built-in electric currentsensor of a controller 6, to thus calculate the amount of electriccurrent at the four metal electrode 4, respectively, and to therebyrecognize a touch point.

However, the capacitive touch screen panel shown in FIG. 1 detects theamount of micro-current, and requires an expensive detecting device, tothus raise the price of the capacitive touch screen panel, and make itdifficult to recognize multiple touches.

In recent years, in order to overcome such problems, the capacitivetouch screen panel shown in FIG. 2 has been chiefly used. The touchscreen panel of FIG. 2 includes a transverse linear touch pad 5 a, alongitudinal linear touch pad 5 b, and a touch drive IC (IntegratedCircuit) 7 for analyzing a touch signal. The touch screen panel detectsa magnitude of a capacitance that is formed between the linear touch pad5 and the finger 8. Here, the touch screen panel scans the transverselinear touch pad 5 a and the longitudinal linear touch pad 5 b to thusdetect a touch signal and to thereby recognize a plurality of touchpoints.

However, when the touch screen panel is mounted on a display device suchas a liquid crystal display (LCD) and is used, it may be difficult todetect a signal due to noise. For example, the liquid crystal display(LCD) uses a common electrode and an alternating-current (AC) commonvoltage (Vcom) is applied the common electrode in some cases. The commonvoltage Vcom of the common electrode acts as noise when detecting touchpoints.

FIG. 3 shows an example in which a conventional capacitive touch screenpanel is installed on a liquid crystal display (LCD). A display device200 such as the liquid crystal display (LCD) has a structure that liquidcrystal is sealed and filled between a lower-side thin film transistor(TFT) substrate 205 and an upper-side color filter 215 to thereby form aliquid crystal layer 210. To seal the liquid crystal, the TFT substrate205 and the color filter 215 are joined by sealants 230 at their outerportions. Although they are not shown, polarizing plates are attached onthe top and bottom of the LCD panel, and besides back light units (BLUs)are provided.

As shown, a touch screen panel is provided on top of the display device200. The touch screen panel has a structure that the linear touch pad 5is put on the upper surface of the substrate 1. A protection panel 3 forprotecting the linear touch pad 5 is attached on top of the substrate 1.The touch screen panel is bonded to the edge portion of the displaydevice 200 through the medium of an adhesive member 9 such as a doubleadhesive tape (DAT), and an air gap 9 a is formed between the displaydevice 200 and the touch screen panel.

In this configuration, if a touch occurs as shown in FIG. 3, acapacitance Ct is formed between the finger 8 and the linear touch pad5. Meanwhile, as shown, a capacitance Cvcom is formed between the lineartouch pad 5 and a common electrode 220 formed on the lower surface ofthe color filter 215 of the display device 200, and an unknown parasiticcapacitance Cp due to capacitive couplings between patterns ormanufacturing process factors also functions at the linear touch pad 5.Thus, the same circuit as an equivalent circuit of FIG. 4 is configured.

Here, the conventional touch screen panel recognizes a touch bydetecting an amount of change in the capacitance Ct, where thecomponents such as the capacitances Cvcom and Cp act as noise at thetime of detecting the capacitance Ct. For example, small- andmedium-sized LCDs for mobile devices employ a line inversion method inwhich the common voltage Vcom of the common electrode 220 alternates byone or a plurality of gate lines as shown in FIG. 5, in order to reducecurrent consumption, and thus the alternating electric field acts asconsiderable noise at the time of detection of touches.

Typically, in order to remove the noise, the air gap 9 a is placedbetween the touch screen panel and the display device 200 as shown inFIG. 3. In addition, although it is not shown, an ITO layer is coated onthe lower surface of the substrate 1 of the touch screen panel, tothereby form a shield layer. In addition, the shield layer is groundedwith the ground signal.

However, in the case of the conventional art, products become thick andthe quality of the products deteriorates due to the air gap 9 a. Inaddition, the conventional art requires a separate shield layer and amanufacturing process of configuring the shield layer, thereby causing arise of a manufacturing cost. In particular, in the case of forming abuilt-in touch screen panel in a liquid crystal display (LCD), it isvery difficult to form the air gap 9 a or the shield layer, and thus itis also very difficult to form the built-in touch screen panel in adisplay device such as the liquid crystal display (LCD).

DISCLOSURE Technical Problem

In order to solve the above-mentioned problems of a conventional touchscreen panel, it is an object of the present invention to provide atouch detection device, touch detection method, and touch screen panel,which acquires a touch signal by using a driving back phenomenon thatcauses a difference between voltages in magnitude that are detected froma touch detector according to a magnitude of a touch capacitance, when adriving capacitor is connected to the touch detector, a driving voltageis applied through one end of the driving capacitor, and the touchcapacitance is formed between a touch input instrument such as a fingerand a touch pad, to thereby minimize an influence due to noise of acommon electrode of a display device, and an influence due to aparasitic capacitance, to thereby stably acquire the touch signal, andto thereby simultaneously facilitate to incorporate a built-in touchscreen panel in the display device such as a liquid crystal display(LCD).

Technical Solution

To attain the above object of the present invention, according to anaspect of the present invention, there is provided a touch detectiondevice that is attached on top of a display device and detectsoccurrence of a touch capacitance (Ct) by an approach of a bodily fingeror a touch input instrument such as a conductor similar to the bodilyfinger, the touch detection device comprising: a touch pad that formsthe touch capacitance (Ct) between the touch input instrument and thetouch pad; a driving capacitor (Cdrv) whose one side is connected to thetouch pad and to the other side of which a driving voltage for detectionof a touch input is applied; a common voltage detector that detects acommon voltage generated from the display device; a driving voltagegenerator that generates the driving voltage in synchronization with thecommon voltage; and a touch detector that is connected to the touch pad,and that detects a touch signal by using a driving back phenomenon whenthe touch capacitance (Ct) is added to the driving capacitor (Cdrv)according to occurrence or non-occurrence of a touch in the touch inputinstrument.

According to an embodiment of the present invention, a common electrodecapacitance (Cvcom) is formed between the touch pad and a commonelectrode of the display device.

According to another embodiment of the present invention, a drivingcapacitor (Cdrv) is not connected to the common voltage detector.

According to a further embodiment of the present invention, the touchpad is connected to the touch detector or the common voltage detector.

According to a further embodiment of the present invention, a chargingunit for applying a pre-charging voltage is connected to the touch padconnected to the common voltage detector.

According to a further embodiment of the present invention, the chargingunit is a switching device and an output portion of the switching deviceconnected to the touch pad connected to the common voltage detector isin a high impedance state upon detection of the common voltage.

According to a further embodiment of the present invention, the input ofthe common voltage detector is in a high-impedance state.

According to a further embodiment of the present invention, the signaloutput from the common voltage detector is input to a comparator todetect whether the common voltage is high (Hi) or low (Low).

According to a further embodiment of the present invention, an upperreference voltage for detecting the high state of the common voltageand/or a lower reference voltage for detecting the low state of thecommon voltage is input to the comparator as a comparison voltage.

According to a further embodiment of the present invention, the chargingunit of the common voltage detector is maintained in an off-state for apredetermined time and detects the common voltage in the off-state.

According to a further embodiment of the present invention, the chargingunit (12) of the common voltage detector (15) carries out an ON/OFFoperation in synchronization with the common voltage.

According to a further embodiment of the present invention, one or moretouch pads (10) are successively used as the touch pad (10) connected tothe common voltage detector (15).

According to a further embodiment of the present invention, when thetouch pad connected to the common voltage detector is connected to thetouch detector, another touch pad is connected to the common voltagedetector to detect the common voltage.

According to a further embodiment of the present invention, the touchdetection device further comprises an output unit for outputting thesignal of the common voltage detector to the outside of a touch driveintegrated circuit (TDI).

According to a further embodiment of the present invention, the touchdetection device further comprises an output determination unit fordetermining whether or not the signal of the common voltage detector isoutput to the outside of a touch drive integrated circuit (TDI).

According to a further embodiment of the present invention, the drivingvoltage is applied to one side of the driving capacitor (Cdrv) insynchronization with the rising edge or the falling edge of the commonvoltage.

According to a further embodiment of the present invention, the chargingunit of the touch detector is a switching device.

According to a further embodiment of the present invention, the chargingunit of the touch detector carries out an ON/OFF operation insynchronization with the common voltage.

According to a further embodiment of the present invention, the touchdetection device further comprises a setting unit for setting thecharging time of the charging unit.

According to a further embodiment of the present invention, the drivingvoltage is applied to one side of the driving capacitor (Cdrv) insynchronization with the common voltage or the charging time.

According to a further embodiment of the present invention, the touchsignal is detected after a predetermined time elapses since theapplication of the driving voltage.

According to a further embodiment of the present invention, the touchdetection device further comprises a start point-in-time determinationunit for determining a start point-in-time at which the touch signal isdetected since the application of the driving voltage.

To attain the above object of the present invention, according toanother aspect of the present invention, there is also provided a touchdetection device that detects occurrence of a touch capacitance (Ct) byan approach of a bodily finger or a touch input instrument such as aconductor similar to the bodily finger, the touch detection devicecomprising: a touch pad that forms the touch capacitance (Ct) betweenthe touch input instrument and the touch pad; a driving capacitor (Cdrv)whose one side is connected to the touch pad and to the other side ofwhich a driving voltage for detection of a touch input is applied; adriving voltage generator that generates the driving voltageperiodically according to a set value; and a touch detector that isconnected to the touch pad, and that detects a touch signal by using adriving back phenomenon when the touch capacitance (Ct) is added to thedriving capacitor (Cdrv) according to occurrence or non-occurrence of atouch in the touch input instrument.

According to another embodiment of the present invention, the chargingunit of the touch detector is a switching device.

According to a further embodiment of the present invention, the chargingunit of the touch detector carries out an ON/OFF operation insynchronization with a detection cycle.

According to a further embodiment of the present invention, the touchdetection device further comprises a detection cycle determination unitfor determining the detection cycle.

According to a further embodiment of the present invention, the touchdetection device further comprises a setting unit for setting thecharging time of the charging unit.

According to a further embodiment of the present invention, the drivingvoltage is applied to one side of the driving capacitor (Cdrv) insynchronization with the charging time.

According to a further embodiment of the present invention, the touchsignal is detected after a predetermined time elapses since theapplication of the driving voltage.

According to a further embodiment of the present invention, the touchdetection device further comprises a start point-in-time determinationunit for determining a start point-in-time at which the touch signal isdetected since the application of the driving voltage.

According to a further embodiment of the present invention, the drivingvoltage applied to the other side of the driving capacitor (Cdrv) is analternating voltage alternating at a predetermined frequency.

According to a further embodiment of the present invention, the touchdetection device further comprises a variation unit for varying amagnitude of the driving capacitor (Cdrv).

According to a further embodiment of the present invention, the drivingcapacitor (Cdrv) is not connected to the touch detector (14).

According to a further embodiment of the present invention, the touchdetector (14) detects a driving back phenomenon in the touch pad (10) atthe rising time and/or the falling time of the driving voltage appliedto the driving capacitor (Cdrv).

According to a further embodiment of the present invention, the touchdetector (14) detects a driving back phenomenon causing a difference inmagnitude of the voltage detected by the touch detector when the touchcapacitance (Ct) is added by occurrence of the touch input in comparisonwith a magnitude of the voltage detected in the touch detector at thenon-occurrence of the touch input.

According to a further embodiment of the present invention, the voltagedetected in the touch detector at the non-occurrence of the touch inputis determined by Equation 1, the voltage detected by the touch detectorwhen the touch capacitance (Ct) is added is determined by Equation 2,and the driving back phenomenon is caused by a difference betweenEquations 1 and 2,

$\begin{matrix}{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{Vh} - {Vl}} \right)\;\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp}}}}} & {{Equation}\mspace{14mu} 1} \\{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{Vh} - {Vl}} \right)\;\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp} + {Ct}}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

in which ΔVsensor is the voltage detected by the touch detector, and Vhis a high level voltage applied to the driving capacitor, Vl is a lowlevel voltage applied to the driving capacitor, Cdrv is the drivingcapacitance, Cvcom is the common electrode capacitance, Cp is theparasitic capacitance, and Ct is the touch capacitance.

According to a further embodiment of the present invention, the touchdetector (14) detects a touch area of the touch input instrument withrespect to the touch pad (10) corresponding to the driving back inmagnitude.

According to a further embodiment of the present invention, the touchdetector (14) comprises an amplifier (18) for amplifying the detectedvoltage.

According to a further embodiment of the present invention, sensorsignal wires (22) connected to the touch pad (10) that detectsoccurrence of the touch input are present in the left and right sides ofthe touch pad (10), in which the sensor signal wires (22) connected tothe touch pad (10) that does not detect any touch input are in afloating state.

According to a further embodiment of the present invention, the sensorsignal wires (22) connected to the touch pad (10) excluding the sensorsignal wires (22) connected to the touch pad (10) that detectsoccurrence of the touch input are in a floating state.

According to a further embodiment of the present invention, sensorsignal wires (22) connected to the touch pad (10) that detectsoccurrence of the touch input are present in the left and right sides ofthe touch pad (10), in which the sensor signal wires (22) connected tothe touch pad (10) that does not detect any touch input are in afloating state before the charging unit (12) of the touch detector isturned on.

According to a further embodiment of the present invention, the sensorsignal wires (22) connected to the touch pad (10) excluding the sensorsignal wires (22) connected to the touch pad (10) that detectsoccurrence of the touch input are in a floating state before thecharging unit (12) of the touch detector is turned on.

According to a further embodiment of the present invention, the touchpad (10) connected to the touch detector (14) is separated from thetouch detector (14) after the driving voltage is applied to the drivingcapacitor connected to the touch detector (14).

According to a further embodiment of the present invention, the touchpad (10) connected to the touch detector (14) is separated from thetouch detector (14) within 1 ns to 100 us after the driving voltage isapplied to the driving capacitor connected to the touch detector (14).

According to a further embodiment of the present invention, the touchpad separated from the touch detector is re-connected to the touchdetector after sensing of the touch input is completed, or apredetermined voltage is applied to the touch pad.

According to a further embodiment of the present invention, thepredetermined voltage is a ground (GND) or a DC voltage of apredetermined size.

According to a further embodiment of the present invention, apredetermined voltage is applied to the touch pad (10) that does notdetect any touch input in a floating state after the touch detector hascompleted a touch sensing operation.

According to a further embodiment of the present invention, thepredetermined voltage is a ground (GND) or a DC voltage of apredetermined size.

According to a further embodiment of the present invention, a pluralityof touch pads are present in which resistance of a section that isconnected to a connection portion where touch signal wires connected tothe touch pad (10) are connected with a touch drive integrated circuit(TDI) is included in a range from −100% to +100%.

According to a further embodiment of the present invention, separationtime of the touch pads connected to the touch detector is equallyapplicable to the plurality of touch pads.

Advantageous Effects

In a touch detection device, touch detection method, and touch screenpanel, using a driving back phenomenon, and a display device with abuilt-in touch screen panel, according to the present invention, changesin the state of a common voltage are detected, a driving voltage isapplied through a driving capacitor connected to a touch detector whileavoiding a point in time of the changes of the state of the commonvoltage, occurrence of a driving back phenomenon is detected in thetouch detector by a touch capacitance added by a touch input, to therebyacquire a touch signal, in the case that a common electrode of thedisplay device has a common voltage level alternating at a predeterminedfrequency, the common electrode of the display device has adirect-current (DC) level, or the common electrode of the display devicealternates at an unqualified unspecified frequency.

As a result, influences due to a parasitic capacitance generated bynoise, a coupling phenomenon, or other factors are minimized, anderroneous recognition of signals does not occur. In addition, thepresent invention detects a touch input at a relatively high voltagelevel, to thus easily capture a signal even with a small cross-sectionalarea of a touch input instrument, and to thereby make it possible toperform a stylus pen input. In addition, the present invention obtains atouch share ratio of a touch input instrument depending on the magnitudeof a driving back, to thus increase touch resolution and enable finehandwriting and drawing. In addition, the present invention mayconfigure an active region of a touch screen panel into a single-layer,to thus simplify a manufacturing process and provide an effect ofobtaining an excellent yield.

DESCRIPTION OF DRAWINGS

The above and other objects and advantages of the invention will becomemore apparent by describing the preferred embodiments with reference tothe accompanying drawings in which:

FIG. 1 is a perspective view showing an example of a conventional touchscreen panel;

FIG. 2 is a plan view showing another example of a conventional touchscreen panel:

FIG. 3 is a cross-sectional view showing an example in which the touchscreen panel of FIG. 2 is mounted on top of a display device;

FIG. 4 is an equivalent circuit diagram showing that a touch capacitanceis detected in FIG. 3;

FIG. 5 is a waveform diagram illustrating a common voltage waveform of aliquid crystal display device;

FIG. 6 is a diagram conceptually showing a typical three-terminal typeswitching device;

FIG. 7 is a conceptual view depicting a principle of detecting a touchinput:

FIG. 8 is a circuit diagram illustrating a basic structure of a touchdetection device according to an embodiment of the present invention;

FIGS. 9A and 9B are graphs showing a correlation between a breakdownvoltage of a touch drive integrated circuit (TDI) and a pre-chargingvoltage thereof:

FIG. 10 is a circuit diagram illustrating a touch detection deviceaccording to another embodiment of the present invention;

FIG. 11 is a circuit diagram illustrating a touch detection deviceaccording to still another embodiment of the present invention:

FIG. 12 is a cross-sectional view showing a configuration of touch padsaccording to an embodiment of the present invention;

FIG. 13 is a cross-sectional view showing a configuration of touch padsaccording to another embodiment of the present invention;

FIGS. 14A and 14B are views showing an example of a configuration ofgesture using an area;

FIGS. 15A to 15C are views showing another example of a configuration ofgesture using an area;

FIG. 16 is a waveform diagram illustrating a process of detecting atouch signal in the present invention:

FIG. 17 is a circuit diagram illustrating a configuration of a commonvoltage detector according to an embodiment of the present invention;

FIG. 18 is a waveform diagram of a common voltage detected by a commonvoltage detection circuit.

FIG. 19 is a detailed circuit diagram illustrating a common voltagedetection circuit according to an embodiment of the present invention;

FIG. 20 is a waveform diagram illustrating a method of recovering acommon voltage detection error when the common voltage detection erroroccurs according to an embodiment of the present invention;

FIG. 21 is a flow chart view illustrating factory calibration forextracting a common voltage component;

FIG. 22 is a waveform diagram illustrating a method of detecting a touchsignal in synchronization with a common voltage according to anembodiment of the present invention;

FIG. 23 is a waveform diagram illustrating an example of an actuallydetected common voltage;

FIG. 24 is a table diagram illustrating a configuration that size of adriving voltage (Vdrv) is changed in accordance with a register set;

FIG. 25 is a circuit diagram illustrating a touch screen panel accordingto an embodiment of the present invention;

FIGS. 26A to 26C are schematic views illustrating a variety ofconfigurations of a touch pad according to an embodiment of the presentinvention;

FIG. 27 is a view illustrating a touch screen panel shown in FIG. 5 inthe laid-open patent publication;

FIG. 28 is a schematic view showing a conventional wiring diagram ofsensor signal wires that are arranged on top and bottom of touch pads;

FIG. 29 is a diagram illustrating a configuration of a differentialamplifier used in the present invention;

FIG. 30 is a diagram illustrating a configuration that ananalog-to-digital-converter (ADC) conversion unit is connected to anoutput of an amplifier;

FIG. 31 is a flow chart view illustrating a factory calibration method;

FIG. 32 is a diagram illustrating an example of setting regions for realtime calibration (RTC) according to an exemplary embodiment of thepresent invention;

FIG. 33 is a circuit diagram illustrating a conventional capacitivetouch signal detection device;

FIG. 34 is a diagram illustrating a configuration of a thin filmtransistor (TFT) on a transverse electric field mode liquid crystaldisplay (LCD) substrate;

FIG. 35 is a cross-sectional view illustrating a conventional backgroundconfiguration on a transverse electric field mode liquid crystal display(LCD) substrate;

FIG. 36 is a cross-sectional view illustrating a backgroundconfiguration on a transverse electric field mode liquid crystal display(LCD) substrate according to an exemplary embodiment of the presentinvention;

FIG. 37 is a front view of a configuration in which a touch detectiondevice is applied to a transverse electric field mode LCD substrateaccording to an exemplary embodiment of the present invention;

FIG. 38 is a circuit diagram illustrating a configuration in which touchpads are used as a background according to an exemplary embodiment ofthe present invention;

FIG. 39 is a diagram illustrating a layout of sensor signal wires (22)according to an exemplary embodiment of the present invention;

FIGS. 40A to 40C are diagrams respectively illustrating a space fillerbetween the touch detector and the sensor signal wires according to anexemplary embodiment of the present invention;

FIG. 41 is a circuit diagram illustrating a configuration of a touchdetection error by a conductor according to an exemplary embodiment ofthe present invention;

FIG. 42 is a waveform diagram illustrating a configuration of openingnon sensing pads according to an exemplary embodiment of the presentinvention;

FIG. 43 is a waveform diagram illustrating a configuration of openingsensing pads according to an exemplary embodiment of the presentinvention;

FIGS. 44A and 44B are schematic diagrams illustrating a configuration ofextracting touch coordinates from data detected or calculated by a touchsensor, according to an exemplary embodiment of the present invention;

FIG. 45 is a diagram illustrating a configuration of detecting a touchsignal and the common voltage by touch pads, according to an exemplaryembodiment of the present invention;

FIG. 46 is a diagram illustrating the use of function keypads accordingto an exemplary embodiment of the present invention;

FIG. 47 is a configurational diagram illustrating the implementation offunction keypads according to an exemplary embodiment of the presentinvention;

FIG. 48 is a table diagram illustrating a configuration of settingregisters applied to the function keypads according to an exemplaryembodiment of the present invention;

FIG. 49 is a diagram illustrating the structure of function key padsaccording to an exemplary embodiment of the present invention;

FIG. 50 is a diagram illustrating a conventional configuration of anedge portion of a touch screen panel;

FIG. 51 is a diagram illustrating a configuration of an edge portion ofa touch screen panel according to an exemplary embodiment of the presentinvention;

FIG. 52 is a diagram illustrating a configuration of a plurality oftouch drive integrated circuits (TDIs) used in the present invention,according to an exemplary embodiment of the present invention;

FIG. 53 is a diagram illustrating a configuration for discharging thestatic electricity according to an exemplary embodiment of the presentinvention;

FIG. 54 is a cross-sectional view showing a configuration of a displaydevice with a built-in touch screen panel according to an embodiment ofthe present invention;

FIG. 55 is an exploded perspective view a display device with a built-intouch screen panel according to an embodiment of the present invention;and

FIG. 56 is a diagram illustrating a configuration of determining a touchgroup according to an embodiment of the present invention.

BEST MODE

Hereinbelow, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

First, the present invention relates to a touch detection device, touchdetection method, and touch screen panel, using a driving backphenomenon, and a display device with a built-in touch screen panel. Aconventional touch detection device detects a magnitude of capacitancedue to contact of a finger and the like, but the touch detection deviceaccording to the present invention detects a driving back phenomenoncaused by a change in magnitude of a touch capacitance, when analternating driving voltage is applied to an added driving capacitor. Atouch detecting system according to the present invention compares avoltage that is generated due to a driving capacitor, a common electrodecapacitance, and a parasitic capacitance at the time of non-occurrenceof a touch input, with a voltage that is generated by a driving backphenomenon when a touch capacitance is added to the common electrodecapacitance at the time of occurrence of a touch input, and thus detectsa difference in magnitudes between the two voltages, to thus minimizeinfluences caused by external noise or a parasitic capacitance, and tothereby acquire a touch signal more reliably.

The display devices referred to in the present invention, may be LCDs(Liquid Crystal Displays), PDPs (Plasma Display Panels), OLED (OrganicLight Emitting Diode) displays, and AMOLED (Active Matrix Organic LightEmitting Diode) displays or any other means of displaying imagesthereon.

LCDs (Liquid Crystal Displays) of the above-listed display devices needa common voltage (Vcom) for operation of liquid crystals. As an example,small and medium-sized LCDs for mobile devices employ line inversiondriving methods in which a common voltage of a common electrodealternates for one or a plurality of gate lines, to reduce the currentconsumption. As another example, large-sized LCDs are configured toemploy dot inversion driving methods in which a common voltage of acommon electrode has a constant DC level. As still another example,transverse electric field mode LCDs display images by line or dotinversion driving methods in which a common electrode is formed in apart of an area on a TFT substrate of each LCD. In the case oftransverse electric field mode LCDs, a back ground is commonly formed inthe entire color filter exposed to the outside through a rear surfaceITO (indium tin oxide) film, and grounded into the ground signal to shutoff the external electrostatic discharge (ESD).

In the present invention, in addition to the electrodes to which theabove common voltage (Vcom) is applied, all the electrodes playing acommon role in a display device are referred to as “common electrodes”and an alternating voltage or a DC voltage or a voltage alternating atan unspecified frequency is referred to as a “common voltage.”

The present invention detects a non-contact touch input of a finger or atouch input instrument having electrical characteristics similar to thefinger. Here, the term “non-contact touch input” means that a touchinput instrument of a finger and the like performs a touch input at astate spaced by a predetermined distance apart from a touch pad by asubstrate. The touch input instrument may contact an outer surface ofthe substrate. However, even in this case, the touch input instrumentand the touch pad remain in a non-contact state. Therefore, a touchaction of a finger on a touch pad may be expressed in the term“approach.” Meanwhile, since a finger remains in a contact state for anouter surface of the substrate, a touch action of a finger on thesubstrate may be expressed in the term “contact.” In this specificationand claims, the terms “approach” and “contact” are commonly used as thesame meanings as above.

The components such as “˜portion” are an aggregate of unit functionelements that perform certain functions. For example, an amplifier foramplifying a certain signal is a unit function element, and an aggregateof amplifiers or signal converters may be named as a signal conversionportion. In addition, the components such as “˜portion” can be includedin larger components or can include smaller components. In addition, thecomponents such as “˜portion” may contain their own central processingunits (CPUs) therein.

In the following drawings, thickness or areas have been enlarged todefinitely show several layers and areas. Through the whole detaileddescription of the specification, like reference numerals are used forlike elements. When it is mentioned that a portion such as a layer, afilm, an area and a substrate is placed “on” or “on the upper surface”of another portion, this means that the portion is not only placed“justly on” the other portion but also the former is placed on a thirdportion between the former and the latter. In contrary, when it ismentioned that a certain portion is placed “justly on” another portion,this means that there are no other portions between them.

In addition, the signal described herein, collectively refer to, unlessotherwise stated, voltage or current.

In addition, in the present specification, the term “capacitance” is thephysical capacity, and is used as the same meaning as the term“electrostatic capacity.” On the other hand, the term “capacitor” refersto an element having a capacitance representing the physical capacity.The capacitance may be made by a designed value and process, orindirectly made as being naturally produced between two signal wiresparallel at a distance from each other. In the present specification,both directly and indirectly created capacitors shall be named“capacitor” without any discrimination.

In addition, in the present specification, the term “forcing a signal”means that a level of a signal which has already maintains any conditionis changed, or gains access to a certain signal in a floating state. Forexample, a meaning of forcing a signal to an ON/OFF control terminal ofa switching device may be used as a meaning of changing an existing lowlevel voltage into a high level voltage, or used as a meaning ofapplying a certain voltage to an ON/OFF control terminal of a switchingdevice that is in a floating state without having any signal, in orderto turn on/turn off the switching device.

In addition, in the present invention, the term “driving backphenomenon” or “driving back” is synonymous with each other, and used as“D/B” in abbreviation.

In addition, in the present invention, the touch drive integratedcircuit (IC) is abbreviated as TDI.

In addition, in the present invention, a voltage caused due to D/B whena touch does not occur, or a voltage caused due to D/B when a touchoccurs, and thus it is determined whether or not a touch occurs and howmay contact area of a touch device is, using correlation or relationshipbetween the two voltages. Accordingly, a meaning of detecting a voltagecaused due to D/B is used in the same meaning as that of detecting atouch signal.

FIG. 6 is a conceptual diagram showing a three-terminal type switchingdevice from among switching devices that are used as examples of acharging unit in the present invention. Referring to FIG. 6, thethree-terminal type switching device includes three terminals having anON/OFF control terminal (indicated as “Cont” in FIG. 6), an inputterminal (indicated as “In” in FIG. 6), and an output terminal(indicated as “Out” in FIG. 6). The ON/OFF control terminal is a controlterminal for controlling the ON/OFF operations of the switching device.If a predetermined magnitude of voltage or current is applied to theON/OFF control terminal, voltage or current that is applied to the inputterminal is output in the form of voltage or current via the outputterminal.

The three-terminal type switching device referred to as the chargingunit in the present invention may be for example, a relay, a MOS (MetalOxide Semiconductor) switch, a BJT (Bipolar Junction Transistor) switch,a FET (Field Effect Transistor) switch, a MOSFET (Metal OxideSemiconductor Field Effect Transistor) switch, an IGBT (Insulated GateBipolar Transistor) switch, a TFT (Thin Film Transistor) switch, or anOPAMP (OPerational AMPlifier) switch, and may be formed by a homogeneousor heterogeneous combination among these.

The relay may be used as a four-terminal type switching device, inaddition to the three-terminal type switching device. All devices havingan ON/OFF control terminal that turns on/off an input and outputregardless of the number of input and output terminals and whose inputand output are turned on/off by the ON/OFF control terminal, may be usedas the charging unit.

Meanwhile, a CMOS (Complementary Metal Oxide Semiconductor) switch isformed by a mutual combination of PMOS (P-channel MOS) and NMOS(N-channel MOS) switches as an example of the three-terminal typeswitching device, in which input and output terminals are connected toeach other, but the ON/OFF control terminal exists separately and isconnected to an identical control signal, or is connected separately toindividual control signals, to thus determine an ON/OFF state of theswitch. The relay is a device that when a current is applied to acontrol terminal, a voltage or current applied to the input terminal isoutput without loss. The BJT switch is a device in which a certainamount of amplified current flows from a collector terminal thereof toan emitter terminal thereof when a current is applied to a base terminalthereof at a state where a current higher than a threshold voltage ofthe base terminal has been applied to the base terminal. In addition,the TFT switch is a switching device that is used in a pixel unit fordisplay device such as a LCD or AMOLED, and includes a gate terminalthat is a control terminal, a source terminal that is an input terminal,and a drain terminal that is an output terminal, in which the TFT switchis energized when a voltage higher than a threshold voltage higher thana voltage applied to the drain terminal is applied to the gate terminal,and thus a current depending on the magnitude of a voltage applied tothe gate terminal flows from the input terminal to the output terminal.

Prior to describing embodiments of the present invention, a principlethat detects a touch input in the present invention will be describedbriefly with reference to FIG. 7. As shown in FIG. 7, it is assumed thatwhen a finger 25 or a conductive touch unit similar to the fingerapproaches to a touch pad 10, a distance between the finger 25 and thetouch pad 10 is an interval “d” and an opposite area is “A.” Anelectrostatic capacitance “C” is formed between the finger 25 and thetouch pad 10 as shown in a right-side equivalent circuit of FIG. 7 and anumerical Equation. If a voltage or current signal is applied to asignal input line of the touch pad 10 having the electrostaticcapacitance “C,” charges of a magnitude “Q” are accumulated in acapacitor having the magnitude of the electrostatic capacitance “C” andthus the capacitor can accumulate charges by a voltage relationshipEquation formed as V=Q/C. As a result, the electrostatic capacitance “C”accumulates the charges “Q.” In the present invention, when a drivingback having a correlation with respect to the magnitude of theelectrostatic capacitance “C” occurs in the touch pad 10 connected withthe touch detector, a touch input is detected by using the detecteddriving back.

FIG. 8 is a circuit diagram illustrating a basic structure of a touchdetection device according to the present invention. Referring to FIG.8, the touch detection device according to the present invention has abasic structure including a charging unit 12, a touch pad 10, a sensorsignal wire 22, a driving capacitor Cdrv, a common electrode capacitorCvcom, and a touch detector 14.

The charging unit 12 supplies a pre-charge signal to the touch pad andis turned off by a turn-off signal supplied to the ON/OFF controlterminal indicated as “Cont” in FIG. 6, to thus make an output terminal12-1 become in a high impedance state.

The pre-charge signal is a voltage that is applied to all capacitorsconnected to the touch detector 14 as a constant DC voltage to chargethe capacitors, prior to detecting touch inputs. Thus, the charging unit12 is a switching device that performs a switching operation accordingto a control signal supplied to the ON/OFF control terminal, or a lineardevice such as an OPAMP that supplies a signal based on a controlsignal.

As shown in FIG. 8, when a three-terminal type switching device isapplied as the charging unit 12, a proper charging voltage may besupplied to all capacitors connected to the output terminal 12-1 of thecharging unit 12, for example, the touch pad 10, the driving capacitorCdrv, and the common electrode capacitor Cvcom, at a required point intime by using a control signal supplied to the ON/OFF control terminaland a signal fed to the input terminal. A DC voltage including zero V,or an alternating AC voltage such as square, triangular or sinusoidalwaves, may be used as the charging voltage.

This charging voltage has a relationship with a voltage that is used ina touch drive integrated circuit (IC) (hereinafter abbreviated as TDI)in which a touch detection system has been integrated. Such arelationship will be described below with reference to FIGS. 9A and 9Bas an example.

A breakdown voltage of a TDI is 5V. Assuming TDI is broken when avoltage of 5V or more is supplied to the TDI, an operation voltage of aninternal circuit in the TDI should not exceed 5 V. As in the embodimentsof FIGS. 9A and 9B, it is assumed that a potential difference caused dueto D/B which will be described later is 3 V. Here, as shown in FIG. 9A,when a voltage of the output terminal 12-1 in the charging unit 12 is 3V before the D/B occurs as shown in FIG. 9A, the voltage of the outputterminal 12-1 in the charging unit 12 becomes 6 V. As a result, 6 V thatis the voltage of the output terminal 12-1 exceeds 5 V that is thebreakdown voltage of the TDI, the TDI is placed in a damaged area.

In order to solve this problem, as shown in FIG. 9B, if a voltage of 1 Vis applied to an input terminal of the charging unit at the chargingunit has been turned on and thus all the capacitors connected to anoutput terminal of the charging unit are charged into 1 V, the potentialof the output terminal 12-1 becomes 4 V even if a potential differenceof 3 V occurs due to the aforementioned driving back, and thus the TDIoperates in a safety area.

Thus, according to one embodiment of the present invention, a functionof controlling the charging voltage to control the maximum voltage inthe event of occurrence of the driving back based on the breakdownvoltage of the TDI may be provided.

FIG. 10 is a circuit diagram illustrating a touch detection deviceaccording to another embodiment of the present invention, in which atouch detector 14 is shown in detail. Referring to FIG. 10, the outputterminal 12-1 of the charging unit 12 and all the capacitors connectedwith the output terminal 12-1 are connected to the touch pad 10. Sincethe D/B phenomenon which will be described later occurs a capacitorconnected to the output terminal 12-1 of the charging unit 12, thevoltage caused due to the D/B is transferred to a buffer 14-1 in thetouch detector 14. Since the input terminal of the buffer 14-1 is in thestate of high impedance (hereinafter referred to as Hi-z), the outputterminal 12-1 of the charging unit 12 becomes in the Hi-z state, andthus all capacitors connected between the output terminal 12-1 of thecharging unit 12 and the buffer 14-1 become in the Hi-z state. In thisembodiment, the case that the output terminal 12-1 of the charging unit12 is directly connected to the buffer 14-1 has been exemplified as anexample, but the output terminal 12-1 of the charging unit 12 may beconnected to the terminals of all elements whose input terminals are inthe Hi-z state, for example, such as the gate of a MOS or the gate of aTFT, instead of the buffer 14-1. The reason of making the outputterminal 12-1 of the charging unit 12 and the touch detector 14 be inthe Hi-z state is that the D/B phenomenon which will be described latershould be performed in the Hi-z state to thereby lengthen a detectiontime to have a longer time. That is, since there is no discharge path ofan isolated charge in the Hi-z state, the level of the voltage that isformed due to the D/B is maintained for a long time with variation atminimum.

The signal output from the buffer 14-1 is input to the amplifier 14-2.If an input terminal of the amplifier 4-2 is in the Hi-z state, a pointP in FIG. 10 may be directly connected to the input end of the amplifier14-2.

In the case that the level of the signal at the point P is lowered andthus should be amplified, the signal can be amplified by using a varietyof amplifiers, however, a differential amplifier may be preferably used.The reason is that a pre-charging voltage or a charging voltage whichwill be described later is charged at the point P, and thus it ispossible to remove the charging voltage through the differentialamplifier and amplify only a voltage generated due to the D/B phenomenonat the point P, in the amplification process.

In order to eliminate DC offset such as the charging voltage when thedifferential amplifier is used, the DC voltage should be applied to thenegative terminal of the differential amplifier. A digital-to-analogconverter (DAC) 14-4 should be used or a reference voltage supply “Refvoltage” 14-5 should be used, in order to apply the DC voltage. The “Refvoltage” 14-5 is the reference voltage which is a DC voltage with aconstant potential, and is generated by a power supply unit 47 of FIG.25 which will be described later.

FIG. 10 shows the use of only one ADC corresponding to a touch pad 10,but in the case that a plurality of touch detection circuits are used asshown in FIG. 10, a plurality of ADCs may be used. As more ADCs may beused, it is advantageous that an operation time consumed for calculatingsignals can be reduced.

Although not shown in FIG. 10, filters may be used between variousfunctional portions shown in the touch detector 14. For instance, afilter may be used in the previous stage of the buffer 14-1, and afilter may be used in the front end or rear end of the amplifier 14-2.These filters include various filters such as bandwidth low-passfilters, bandwidth high pass filters, or grass cut filters (GCFs),ranking filters, and average filters by chopping.

The touch pad 10 is formed of a transparent conductor or metal. In thecase that the touch pad 10 is mounted on a display device and is formedas a transparent conductor, the transparent conductor is formed of atransparent conductive material, such as ITO (Indium Tin Oxide), ATO(Antimony Tin Oxide), CNT (Carbon Nano Tube), or IZO (Indium Zinc Oxide)or a transparent material with conductive characteristics similar to theITO, ATO, CNT, or IZO. In the case that the touch pad 10 is not mountedon the display device, but is applied as a touch keyboard or a touch keypad that is used for a refrigerator or monitor, the touch pad 10 may beformed of a non-transmissive material such as metal.

The touch pad 10 may be patterned in various forms. For example, thetouch pad 10 may be arranged in a dot-matrix form in which isolatedislands are arranged in a matrix form in an active region of a touchscreen panel 50 of FIG. 12, or the touch pad 10 may be arranged so thatlinear patterns are arranged lengthwise and crosswise on the touchscreen panel 50. A form of the touch pad 10 will be described in anembodiment to be described later.

The sensor signal wire 22 is a signal wire through which a polarity of acapacitor formed when a finger 25 or a touch unit (for example, such asa touch pen) having a conductive characteristic similar to that of thefinger 25 approaches the touch pad 10 is connected to the touch detector14. Like the touch pad 10, the sensor signal wire 22 may be formed ofthe same conductive transparent material as that of the touch pad 10.However, in some cases, the sensor signal wire 22 may be formed of anon-transmissive material such as metal. The specific embodiments of thesensor signal wire 22 will be described later.

The driving capacitor (Cdrv) is an element to which a driving voltage isapplied for detection of a touch input in the present invention, inwhich one end of the driving capacitor (Cdrv) is connected to the touchdetector 14, and to the other end of which a driving voltage is applied,to thereby generate a D/B phenomenon due to the driving voltage. Here,the reference characters “Cdrv” is a symbol that represents both thename and magnitude of a capacitor. For example, the symbol “Cdrv” meansa capacitor named Cdrv and simultaneously means a capacitance havingCdrv in magnitude. Other capacitor symbols such as Ct, Cvcom and Cp tobe described later represents both the names and magnitudes of thecapacitors.

As illustrated in FIG. 8, the output terminal 12-1 of the charging unit12 is connected to the touch detector 14. In addition, one end of thedriving capacitor (Cdrv) is connected to the output terminal 12-1 of thecharging unit 12, and a detection signal is applied to the other end ofthe driving capacitor (Cdrv). The detection signal is a voltagealternating at a plurality of respectively different potentials, and isa periodic or non-periodic waveform such as a square, sinusoidal, ortriangular wave. A D/B voltage that is proportional to the size of thealternating driving voltage is derived and detected from the touchdetector 14 or the touch pad 10. Accordingly, since the detected D/Bvoltage is detected at a crossing point of the touch detector 14, thetouch pad 10, and the output terminal 12-1 of the charging unit 12, ameaning of detecting the D/B signal from the touch pad 10, the touchdetector 14, or the output terminal 12-1 of the charging unit 12 meansthat the D/B signal is detected at the same position as the crossingpoint of the touch pad 10, the touch detector 14, and the outputterminal 12-1 of the charging unit 12 throughout this specification.

A common electrode capacitor (Cvcom) of FIG. 8 has a capacitance that isformed when the touch pad 10 faces the common electrode of the displaydevice, in which the one side of the common electrode capacitor (Cvcom)is connected to the touch detector 14 and the common voltage is appliedto the other side of the common electrode capacitor (Cvcom). In thiscase, the common voltage may be directly connected to and applied to thecommon electrode capacitor (Cvcom), but the common voltage is usuallyelectromagnetically induced through the medium such as glass or air andapplied to the common electrode capacitor (Cvcom). For example, in FIG.12, the touch pad 10 forms a touch capacitance (Ct) together with thetouch unit such as a finger 25, and also forms the common electrodecapacitance (Cvcom) while interposing a color filter 215 therebetween.

FIG. 11 illustrates a touch detection device according to an embodimentof the present invention, in which MOS (Metal Oxide Semiconductor), TFT(Thin Film Transistor), or FET (Field Effect Transistor) is used as aswitching device. In FIG. 11, an analog to digital converter is used inthe touch detector 14. The ADC performs a function of converting thedetected analog signals to digital signals, and in this embodiment, theADC performs a function of converting the detected touch signal into thedigital signal and transferring the conversion result to a signalprocessor 35 or a CPU 40 of FIG. 25.

As shown in FIG. 11, if a bodily finger 25 approaches the touch pad 10within a certain distance from the touch pad 10, a touch capacitance“Ct” is formed between the finger 25 and the touch pad 10. Ct is a valuethat is set by the relational Equation of FIG. 7, and may be freelyformed by adjusting an interval between a touch unit such as a bodilyfinger 25 and the touch pad 10, and an opposite area of the touch pad10. For example, if the touch pad 10 is selected as a large area, thetouch capacitance “Ct” is also designed to have a large value based onthe relationship Equation of FIG. 7. In contrast, if the touch pad 10 isselected as a small area, the touch capacitance “Ct” is also formed tohave a small value. As an embodiment, the touch capacitance “Ct” may beformed to have a value of tens of fF (femto F) to tens of uF (micro F).

The symbol “Cp” of FIG. 11 is a parasitic capacitor. The “Cp” is the sumof values of capacitors other than capacitors formed by the relationalEquation as “Ct,” or fabricated as “Cdrv” and may be modeled as acapacitor whose one end is connected to the touch detector 14 and theother end of which is connected to any ground. Thus, a plurality ofdifferently grounded parasitic capacitors (Cp) can be formed, but onlyone ground is assumed in the present specification, and only oneparasitic capacitor connected to the only one ground has been shown. Theparasitic capacitor (Cp) may be implemented into one of a variety ofparasitic capacitors such as a parasitic capacitor that occurs betweenthe sensor signal wire 22 and the display device, a parasitic capacitorthat occurs between the sensor signal wires 22 when a plurality of thetouch pads 10 are provided in a dot matrix form as shown in FIG. 25, andthus the sensor signal wires 22 connected to the touch pads 10 are wiredin parallel to each other, a parasitic capacitor that occurs in aconnection portion when a TDI is connected to the touch pad 10, or aparasitic capacitor that occurs due to interference of a circuit portionconnected to the sensor signal wire in the TDI with peripheral circuits.According to Equations 1 and 2 to be described later, these parasiticcapacitors play a role of lowering the D/B signal after being insertedto the denominators of Equations 1 and 2. Thus, it is advantageous todetect touch inputs with no parasitic capacitors included as many aspossible.

Referring back to FIG. 11, a pre-charging voltage (Vpre) is applied tothe input terminal of the charging unit 12, and the pre-charging voltage(Vpre) is output through the output terminal 12-1 when the switchingdevice is turned on by a control voltage (Vg) which is applied to anON/OFF control terminal (cont). Thus, all capacitors connected to theoutput terminal 12-1 of the charging unit 12 are charged as thepre-charging voltage (Vpre).

According to an embodiment, assuming that the switching device is turnedon when Vpre is 3 V and Vg varies from 0 V (Zero Volt) to 10 V, thepotential of the touch detector 14 to which the driving capacitor(Cdrv), the touch capacitance (Ct), and the parasitic capacitor (Cp) areconnected is 3 V after the turn-on of the switching device. After beingcharged at a point P, the control voltage (Vg) of the switching deviceis fallen from 10 V to 0 V to thus turn off the switching device, andthe point “P” of the touch detector is in a high-impedance state, tothus isolate electric charges at the point “P” and then an alternatingdriving voltage is applied to the driving capacitor (Cdrv). In thiscase, the magnitude of the voltage detected at the point “P” isproportional to that of the driving voltage the driving back phenomenonoccurs depending on the magnitude of the capacitors connected to thepoint “P.”

At this point, assuming Cdrv, Cp, and Cvcom are fixed values, and themagnitude of the driving voltage applied to the driving capacitor (Cdrv)is constant, the magnitude of the voltage detected by driving backphenomenon at the point “P” depends on the touch capacitance (Ct). Thus,since the voltage detected in the touch detector 14 varies depending onthe magnitude of the touch capacitance (Ct), it is possible to detectthe presence of the touch input and to compute the opposite area (ortouch area) between the touch pad 10 and the touch input instrument suchas the finger 25, by detecting difference between the driving voltagesdue to driving back phenomenon, and to also find out a touch point.

FIG. 12 is a cross-sectional view showing a configuration of touch padsaccording to an embodiment of the present invention, and FIG. 13 is across-sectional view showing a configuration of touch pads according toanother embodiment of the present invention. FIG. 12 illustrates thatthe touch pads 10 are mounted on a substrate that is formed separatelyfrom the display device, and FIG. 13 illustrates that the touch pads 10are embedded in the display device. Referring to FIGS. 12 and 13, theformation of the common electrode capacitor (Cvcom) will be described asfollows.

As shown in FIG. 12, the display device 200 has the common electrode220. An AMOLED or PDP display device does not have a common electrodethat functions to display the quality of image, but since the commonelectrode capacitor (Cvcom) of FIG. 11 is formed between a variety ofpotentials formed on the TFT substrate of the AMOLED or the drivingsubstrate of the PDP and the touch pads 10 facing the variety ofpotentials, a virtual electric potential that can be formed of thevariety of potentials formed on the TFT substrate of the AMOLED or thedriving substrate of the PDP is also named a common electrode.

The display device 200 may be a display device formed in various formsas described above. The common electrode 220 may be an electrode of acommon voltage (Vcom) in a liquid crystal display (LCD), or may be oneof other types of electrodes. Among a variety of display devices, theLCD has been illustrated in the embodiment of FIG. 12.

In the display device 200 shown in FIG. 12, liquid crystal is sealed andfilled between a lower-side thin film transistor (TFT) substrate 205 andan upper-side color filter 215, to thus have a structure of forming aliquid crystal layer 210. To seal the liquid crystal, the TFT substrate205 and the color filter 215 are joined by sealants 230 at their outerportions. Although they are not shown, polarizing plates are attached onthe top and bottom of the LCD panel, and besides optical sheets such asa back light unit (BLU) and a brightness enhancement film (BEF) areprovided.

As shown, a touch screen panel 50 is provided on top of the displaydevice 200. As shown in FIG. 12, the touch screen panel 50 is attachedto the upper portion of the display device 200 at the outer portionthereof, through the medium of an adhesive member 57 such as a doubleadhesive tape (DAT), and an air gap 58 is formed or a contact member 58is filled between the touch screen panel 50 and the display device 200.The contact member 58 is made of a material such as a permeable siliconeor OCA (Optically Clear Adhesive) or adhesive resin that is used toattach the touch screen panel 50 and the display device 200.

A common voltage level for displaying images is applied to the commonelectrode 220 of the display device 200, in which the common voltage isa DC voltage or a voltage whose amplitude alternates at a predeterminedfrequency. For example, a line-inversion type small-sized LCD has analternating common voltage of the common electrode 220 as shown in FIG.5, and the other dot-inversion type LCDs that are used for a notebookcomputer, monitor, or TV have a common voltage direct-current (DC) levelof a constant magnitude voltage.

As shown, the common electrode capacitor (Cvcom) is formed the touch pad10 and the common electrode 220 of the display device 200. If a certainpre-charge signal is applied to the touch pad 10, the common electrodecapacitor (Cvcom) is charged with the pre-charging voltage grounded bythe common voltage. For example, if the common voltage is 5 V, and thepre-charging voltage is 3 V at the time of the pre-charging, the commonelectrode capacitor (Cvcom) is charged with the pre-charging voltage of3 V grounded by the common voltage of 5 V. Thus, one end of the commonelectrode capacitor (Cvcom) is electrically grounded to the potential ofthe common electrode 220. As a result, in the case that an alternatingvoltage is applied to the common electrode 220, the potential of thetouch pad 10 connected to the other end of the common electrodecapacitor (Cvcom) alternates by the alternating voltage applied to thecommon electrode 220. In the case that such an alternating potentialoverlaps with a touch signal using the D/B phenomenon, the alternatingpotential may cause obstacles to detection of the touch signal. Thus,when the touch signal is detected by using the D/B phenomenon, the touchsignal should be detected by avoiding the rising edge and falling edgeof the alternating common voltage.

Meanwhile, a reference numeral 24 in the drawing denotes a protectivelayer 24 to protect the touch pad 10, in which the protective layer 24is made of glass, plastic, vinyl, or cloth.

FIG. 13 shows an example of a configuration of a touch pad, whichillustrates an embodiment of the case where the touch pad 10 is built inthe display device. Referring to FIG. 13, the touch screen panel 50 maybe formed on top of a color filter 215 that is a part of the displaydevice. As shown, the common electrode 220 is formed at the lowerportion of the color filter 215, and the touch pads 10 are patterned onthe top surface of the color filter. In the FIG. 13 embodiment, theprotective layer 24 is replaced by a polarizer.

Even in the FIG. 13 embodiment, the common electrode capacitance (Cvcom)is also formed between the common electrode 220 and the touch pad 10. Ifan alternating voltage is applied to the common electrode, the electricpotential of the touch pad 10 is induced and alternates by thealternating voltage. The voltage caused by the D/B phenomenon induced bythe alternating potential overlaps with the touch signal detected by theD/B phenomenon induced by the alternating driving voltage applied to thedriving capacitor (Cdrv), and thus influences upon the touch signal.Thus, when the touch signal is detected by using the D/B phenomenon, thetouch signal should be detected by avoiding the rising edge and fallingedge of the alternating common voltage.

Referring back to FIG. 11, the touch capacitance (Ct), the auxiliarycapacitor (Caux), the common electrode capacitance (Cvcom), and theparasitic capacitance (Cp) that are formed between the touch pad 10 anda conductor such as a finger 25 are connected to the output terminal12-1 of the charging unit 12. Thus, when a pre-charge signal such as anyvoltage or current is applied to the input terminal 12-1 of the chargingunit 12 at a state where the charging unit 12 has been turned on, Cdrv,Ct, Cvcom, and Cp are charged in a pre-charge level and thus thepotential of the input end of the touch detector 14 becomes thepre-charge level. Thereafter, if the charging unit 12 is turned off, thepre-charge (or charge) signal level is maintained unless the signalscharged in the four capacitors Cdrv, Ct, Cvcom, and Cp are separatelydischarged from the four capacitors Cdrv. Ct. Cvcom, and Cp.

To stably isolate the charged signals, the output terminal 12-1 of thecharging unit 12 and the input end of the touch detector 14 have ahigh-impedance (or Hi-z) state. Preferably, the output terminal 12-1 ofthe charging unit 12 and the input end of the touch detector 14 have animpedance of at least 100 Kohm. If a touch input is observed whiledischarging the signals charged in the four capacitors, the chargedsignals are isolated in the other ways, or the signals are quicklyobserved at the time of discharge initiation, there is no need toinevitably have a high-impedance (or Hi-z) state at the input end of thetouch detector 14.

The touch detector 14 detects whether or not a signal level of the touchpad 10 is shifted. Preferably, the touch detector 14 detects adifference in the magnitude of a voltage detected by the D/B phenomenonat the time of occurrence of a touch input (that is, when Ct is formed),in contrast to the magnitude of a voltage detected by the D/B phenomenonat the time of non-occurrence of a touch input (that is, when Ct is notformed), to thus acquire a touch signal. The touch detector 14 may havea wide variety of devices or circuit configuration. In the embodimentsto be described later, examples in which a switching device and anamplifier are used as the touch detector 14 will be described, but theconfiguration of the touch detector 14 is not limited thereto.

The output of the buffer 14-1 due to the driving capacitor (Cdrv) andthe driving voltage applied to one end of the driving capacitor (Cdrv)at the time of non-occurrence of a touch input is determined byfollowing Equation 1.

$\begin{matrix}{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{Vh} - {Vl}} \right)\;\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp}}}}} & {{Equation}\mspace{11mu} 1}\end{matrix}$

Since the touch capacitance (Ct) is added in parallel in the touchdetector 14 at the time of occurrence of a touch input, the voltagedetected by the D/B phenomenon at the input end of the touch detector 14is determined by following Equation 2.

$\begin{matrix}{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{Vh} - {Vl}} \right)\;\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp} + {Ct}}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

In Equations 1 and 2, ΔVsensor is a voltage detected by the D/Bphenomenon at the input end of the touch detector 14, Vpre is apre-charging voltage, Vh is a high level voltage of the driving voltageapplied to the driving capacitor (Cdrv), or a turn-on voltage applied toa control terminal of the charging unit 12, Vl is a low level voltage ofthe driving voltage applied to the driving capacitor (Cdrv), Cvom is acommon electrode capacitance, Cp is a parasitic capacitance, and Ct is atouch capacitance.

The touch detector 14 detects voltages generated by Equations 1 and 2,which will be described below in detail.

First, the D/B phenomenon is defined again by using Equations 1 and 2 asfollows. According to the D/B phenomenon, there are one or morecapacitors connected to the driving capacitor. When an alternatingvoltage of a predetermined magnitude is applied to the other side (anend of FIG. 11 through which Vdrv is applied) of the driving capacitor,the potential of the point at which the capacitors are commonlyconnected is proportional to the magnitude of the voltage applied to oneend of the driving capacitor, and has a correlation with respect tocommonly connected capacitors. The correlation that is mentioned heremeans that a sum of the capacitance of all the capacitors connected incommon is located in the denominator and the driving capacitance islocated in the numerator.

According to the difference between Equations 1 and 2, Ct exists in thedenominator of Equation 2. Since the touch capacitance (Ct) is acapacitance formed between the touch pad 10 and the touch unit such as afinger, the capacitance that is the size of Ct varies depending on thepresence or absence of a touch input or a facing area of an opposingdistance between the touch unit and the touch pad 10. Such a variationof Ct may cause a difference between the voltages induced by Equations 1and 2. Thus, if such a voltage difference is detected, it is possible torecognize if a touch input occurs or to calculate a touch area.

In Equations 1 and 2, Vh and Vl represent the high level and low levelof the driving voltage applied to the driving capacitor (Cdrv), and theD/B phenomenon occurs in both cases that the driving voltage is changedfrom high to low and from low to high. If the driving voltage changesfrom a starting point at which Vh=5 V to a point at which Vl=2 V, D/Bwill be proportional to −3V that is −(Vh−Vl), and if the driving voltagechanges from a starting point at which Vl=2 V to a point at which Vh=5V, D/B will be proportional to 3V that is (Vh−Vl).

At the moment the driving voltage alternates from low to high, electriccharges are supplied to the driving capacitor and the charges suppliedto the driving capacitor are supplied to all the capacitors connected inparallel with the driving capacitor, to thus raise the potential of allthe capacitors. Accordingly, the driving voltage caused due to the D/Bphenomenon is as follows.

$\begin{matrix}{{\Delta\;{Vsensor}} = {{Vpre} + {\left( {{Vh} - {Vl}} \right)\;\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp}}}}} & {{Equation}\mspace{14mu} 1\text{-}1}\end{matrix}$

In addition, at the moment the driving voltage alternates from high tolow, charges are discharged from the driving capacitor and all thecapacitors connected in parallel with the driving capacitor, to thusdrop the potential of all the capacitors. Accordingly, the drivingvoltage caused due to the D/B phenomenon is as follows.

$\begin{matrix}{{\Delta\;{Vsensor}} = {{Vpre} + {\left( {{Vh} - {Vl}} \right)\;\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp}}}}} & {{Equation}\mspace{14mu} 1\text{-}2}\end{matrix}$

This way applies identically to the Equation 2.

Meanwhile, Vh and Vl can be easily set, and will be determined in therange of not exceeding the breakdown voltage of TDI. For example,assuming that Vpre=3V and the value by the correlation of the capacitorsis 0.1, the driving voltage caused due to the D/B phenomenon will be 2 Vwhen the driving voltage changes from a starting point at which Vh=10 Vto a point at which Vl=0 V.

Also, Cvcom may be obtained from following Equation 3.

$\begin{matrix}{{Cvcom} = {ɛ\; 1\;\frac{S\; 1}{D\; 1}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

In Equation 3. ∈1 may be obtained from the composite dielectric constant(or permittivity) of media existing between the touch pad 10 and thecommon electrode 220. In the case of FIG. 12, since glass, an air space,a polarization plate, and an adhesive for attaching the polarizationplate onto glass exist between the touch pad 10 and the common electrode220, a composite dielectric constant of these media becomes ∈1 inEquation 3. S1 is an opposite area between the touch pad 10 and thecommon electrode 20, which will be easily calculated. In the case thatthe common electrode 220 is formed over the entire lower surface of thecolor filter 215 as shown in FIG. 12, the opposite area S1 is determinedby an area of the touch pad 10. In addition, D1 is a distance betweenthe touch pad 10 and the common electrode 220, and thus corresponds tothickness of the medium.

As seen, Cvcom is a value that may be easily obtained and set.

The touch capacitance Ct may be obtained from following Equation 4.

$\begin{matrix}{{Ct} = {ɛ\; 2\;\frac{S\; 2}{D\; 2}}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

In Equation 4, the permittivity ∈2 may be obtained from a medium betweenthe touch pad 10 and the finger 25. If a plurality of media are usedbetween the touch pad 10 and the finger 25, a composite dielectricconstant of these media can be obtained. If reinforced glass is attachedon the top surface of the touch screen panel 50, in FIG. 12, thepermittivity ∈2 can be obtained by multiplying the specific dielectricconstant of the reinforced glass by the dielectric constant of vacuum.S2 corresponds to an opposite area between the touch pad 10 and thefinger 25. If the finger 25 covers the entire surface of a certain touchpad 10, S2 corresponds to the area of the certain touch pad 10. If thefinger 25 covers part of a certain touch pad 10, S2 will be reduced fromthe area of the touch pad 10, by an area of the certain touch pad 10that is not covered with the finger 25. In addition, D2 is a distancebetween the touch pad 10 and the finger 25, and thus corresponds tothickness of a protection layer 24 that is put on the upper surface ofthe touch screen panel 50.

As described above. Ct is a value that can be also easily obtained, andthat can be also easily set up by using the material and thickness ofthe protection panel 24 or the reinforced glass that is put on the uppersurface of the touch screen panel 50.

According to Equation 4, since Ct is proportional to the opposite areabetween the finger 25 and the touch pad 10, a touch share of the finger25 with respect to the touch pad 10 can be calculated from the Ct. Amethod of calculating a touch share of the finger 25 is as follows.Considering Equations 1 and 2, a difference between Equations 1 and 2 isa difference in size of a touch capacitance (Ct) according to thepresence or absence of a touch input. Assuming Vh, Vl, Vpre, and Cdrvare fixed values, only Ct can be extracted from Equations 1 and 2.Namely, a relationship Ct=f(ΔVsensor, parallel-connected capacitors, Vh,Vl, Vpre) is established. Assuming that ∈2 and D2 are fixed values inEquation 4, a touch area is proportional to the capacitance. Thus, it ispossible to calculate an area by the extracted Ct.

Further, when an area is obtained by using Equations 1 and 2, both theD/B voltage generated by Equation 1 and the D/B voltage generated byEquation 2 are used. The D/B voltage generated by Equation 1 is a valueset in factory calibration or real time calibration which will bedescribed later, and is an event that has happened earlier than Equation2. The D/B voltage generated by Equation 2 is a voltage generated at thetouch detection time, and thus the touch detection time is later thanthe detection time of the D/B voltage generated by Equation 1. In orderto obtain the touch area in the present invention, both the past D/Bvoltage such as factory calibration or real time calibration and the D/Bvoltage at a point in time when a touch input occurs are used. Forexample, the voltage derived by Equation 1 may be applicable in thedenominator and numerator of a certain term in an equation forcalculating an area, and the voltage derived by Equation 2 may beapplicable in the denominator and numerator of another certain term, inwhich these terms that are different from each other are included in theequation for calculating the area.

Since it is possible to detect an area according to a variation of anopposite area between a finger 25 and the touch pad 10, various gesturescan be carried out by varying a contact area of the finger with respectto the touch pad 10. Referring to FIG. 14A, the finger 25 is in contactwith the touch screen panel 50, and the finger 25 is opposed to ninetouch pads 10. Further, referring to FIG. 14B, the finger 25 is opposedto fifteen touch pads 15. Raising or lowering the single finger varies acontact area between the finger 25 and the touch pad 10, and thus it ispossible to make an image screen (e.g., a landscape or a person, or akeyboard, etc.) displayed on a display device large and small inconjunction with the contact area.

FIGS. 15A to 15C are views showing another example of a configuration ofgesture using an area. U.S. Apple's iPad® has four sides made of blackmatrix (BM) as shown in FIG. 15A, which are screen sections where noimages are displayed as regions where fingers are located when the iPadis ergonomically held with both hands to then watch movies. Such a padseries device has a wide screen of more than 7 inches and thus is mostlyheld with both hands to thus watch an active area (hereafter abbreviatedas A/A) on which images are displayed. Accordingly, BM is essentiallyneeded. However, the BM is a factor that widens the screen size of thedevice where BM has been applied, and thus it may cause a problem ofdegrading the portability.

FIGS. 15B and 15C are views showing another example of a configurationof gesture using an area to solve problems of BM. In FIG. 15B, BM doesnot exist unlike FIG. 15A, and most of the device is made of the A/Aexcept for a BM area of several millimeters (mm) in an absolute screen(e.g., passages along which LCD's gate signal wires or source signalwires pass). If one does not hold the device as he or she watches thedevice upright on a desk or lap, the full screen is displayed on thedevice shown in FIG. 15B.

However, in the case that the device is held by the hand and the fingercontacts one side of the screen, the BM in correlation with the area ofthe finger contacting the screen is displayed on the screen. The BM isnot a BM that is always present as shown in FIG. 15A, but a BM byimages. That is, if the finger is in contact with the screen and thusthe contact area becomes a certain area above, the BM can be displayedinto images in black series by allowing the finger in contact with thescreen to become an interface or a border between the BM and the A/A.Here, since the area marked by the BM should not react with a touch, GUI(Graphic User Interface) such as a touch icon is not included in the BMarea indicated by the black or dark color. Even though GUI is includedin the BM area, reaction by touch should not occur. In addition, in thecase that one finger is pushed deeper into the screen or is put out tothe outside, the BM will be made wider or narrower in conjunction with acontact area between the finger and the screen. If one finger 25contacts the left or right side of the screen or the left and rightsides thereof, it is preferable that the upper and lower BMs areautomatically generated, and an area ratio of the A/A is 4:3 or 16:9.

In addition, if an area of a finger 25 that is in contact with one sideof the screen is smaller than a threshold value that has been set inadvance, the area of the finger 25 may not be recognized as a gesturefor a grip, while if the former is greater than the latter, it isdesirable to generate the BM from that time.

By using the above-described technical principles, a portable electronicdevice varying an area where an image of a display apparatus image isdisplayed on the basis of a gripping area and a position according toone embodiment of the present invention, can be provided.

FIG. 16 is a waveform diagram showing a process for detecting a touchsignal in the embodiment of FIG. 11. Referring to FIG. 16, a method ofdetecting a touch signal by using a driving back phenomenon, will bedescribed as follows.

As mentioned earlier, in one embodiment of the present invention, acommon voltage may be an alternating voltage alternating with a constantfrequency, or a DC voltage that does not alternate or an AC voltage thatalternates aperiodically. In the FIG. 16 embodiment, the common voltagealternates periodically in an area 1 to an area 8, and the commonvoltage having the DC voltage that does not alternate is provided in anarea 11 to an area 15. Accordingly, it can be seen that the presentinvention can be carried out regardless of the form of the commonvoltage.

In order to proceed with the present embodiment, a common voltage shouldbe detected first. If the waveform of the rising edge and falling edgeof the common voltage is applied at an interval at which the drivingback phenomenon is detected in the case that the common voltagealternates with a certain size, the waveforms that are detected in thetouch detector 14 may be distorted due to the waveform of the commonvoltage. Accordingly, the present invention detects the driving backphenomenon while avoiding the points in time at which the rising edgeand falling edge of the common voltage occur. However, in anotherembodiment, as in the exemplary embodiment of the present invention,both a driving back phenomenon that occurs when the driving voltage isapplied to one side of the driving capacitor (Cdrv), and a driving backphenomenon that occurs at the rising edge and falling edge of the commonvoltage may be detected together, to thus detect the touch input.

If a common voltage is a DC level that does no alternate, it is possibleto detect a driving back phenomenon that does not depend on the waveformof the common voltage. A touch drive IC (TDI) 30 that will be describedlater may include a mode setter unit of setting a mode of sensing therising edge and falling edge of the common voltage and referring to thesensed rising edge and falling edge thereof in the case that the commonvoltage alternates, and a mode where the common voltage is not referredto when the common voltage does not alternate. By setting the modesetter unit, when the common voltage does not alternate, the commonvoltage is not detected and is not synchronized with a touch detectionprocess. Thus, it is possible to detect the driving back phenomenoneasily. Once the common voltage is detected and the common voltagealternates, the driving back voltage due to the driving voltage appliedto the driving capacitor (Cdrv) can be detected while avoiding thepoints in time at which the common voltage alternates. Thus, accordingto benefits of this approach, the driving back phenomenon due to thetouch input can be detected in any display devices in which the commonvoltage alternates or does not alternate.

Embodiment in an Area where a Common Voltage Alternates

The waveform of the common voltage is first detected to then detect therising edge or falling edge of the waveform of the common voltage, andthen the ON/OFF control terminal of the charging unit 12 is turned onafter a predetermined time (indicated as ‘t1’ in this embodiment) tothereby pre-charge capacitors. Referring to FIG. 11, the capacitors thatare charged in this embodiment are Cdrv, Ct, Cvom, and Cp. It may begood that Vpre that is the pre-charging voltage is always maintained asthe charging voltage level, or any potential may be used as thepre-charging voltage until the charging voltage level is maintainedimmediately before Vg is turned on.

Referring to FIG. 11, Vpre that is the pre-charging voltage is connectedto the input unit 12-2 of the charging unit 12, and is transferred tothe output unit 12-1 at a state where the charging unit is turned on, tothus charge the capacitors. In this case, a voltage drop due to aresistance between the input unit 12-2 and the output unit 12-1 of thecharge unit 12 has been neglected.

The control voltage (Vg) can be applied in any areas. For example, anarea {circle around (4)} is an interval where the common voltagealternates, and a change in the magnitude of the voltage occurs due tothe D/B caused by the alternating common voltage, but the controlvoltage (Vg) is applied in the interval of the area {circle around (4)}.Thus, a voltage variation due to the common voltage does not occur. Ifthe ON/OFF control terminal of the charging unit 12 is turned off, aftercapacitors have been charged, the output unit 12-1 of the charging unit12 is in the Hi-z state and the input of the touch detector 14 is in theHi-z state by use of the buffer. Accordingly, the charged voltages aremaintained in the capacitors. Likewise, intervals of charging voltagesand maintaining the charged voltages are areas {circle around (1)},{circle around (4)}, and {circle around (7)}. In the areas {circlearound (1)}, {circle around (4)}, and {circle around (7)}, predetermineddischarge may occur due to the fact that the output unit 12-1 of thecharging unit 12 and the input of the touch detector 14 are not in theideal Hi-z state, but such discharge can be neglected in thisembodiment.

In this embodiment, the case that the voltage due to the D/B is detectedat the time the driving voltage is changed from low to high has beenillustrated in which the charging voltage is 2 V. In addition, it wasassumed the amplitude of Vdrv is 10 V, and the calculated value of

$\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp}}$is 0.2. Thus, the voltage in the areas {circle around (2)}, {circlearound (5)}, and {circle around (8)} where the D/B phenomenon occurs is4 V by Equation 1-1. Equation 1-1 represents the detection voltage bythe D/B phenomenon in the case that no touch occurs, and Equation 1-2represents the detection voltage by the D/B phenomenon in the case thata touch occurs.

If a touch has occurred in the area {circle around (7)}, the voltage inan area {circle around (8)} should be changed by Equation 2. Therefore,if the value of

$\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp} + {Ct}}$in Equation 2 is 0.1, the voltage in the area {circle around (8)} is tobe 3 V. As described above, the touch detector 14 detects the voltagewhen a touch has occurred as 3 V on the basis of a voltage of 4 V whenno touch has occurred, and calculates a difference between the detectionvoltage of 3 V and the reference value of 4 V, to thereby judge whetherit has been touched or untouched, and to calculate a touch area.

The time required for the touch detection in touch detecting areas suchas areas {circle around (2)}, {circle around (5)}, and {circle around(8)} is only dozens of microseconds (μs) and the discharge amount of thedetected voltage is insufficient, and thus in the present embodiment,the voltage due to the D/B phenomenon in the areas {circle around (2)},{circle around (5)}, and {circle around (8)} is detected, to thus ignorethe discharge in the areas where it is determined whether or not a touchis detected. Therefore, the voltage due to the D/B becomes 2 V byEquations 1-2 even in the intervals such as areas {circle around (3)}and {circle around (6)} where the driving voltage returns to 0 V.

On the other hand, referring to a boundary region between the areas{circle around (8)} and {circle around (9)}, the boundary region is aninterval where the D/B phenomenon occurs by the common voltage, and thevoltage that is formed when the interval is changed from the area{circle around (8)} to the area {circle around (9)} is being changedsince the common voltage is changed from high to low. Referring toEquations 1 and 2, when the magnitude of the voltage applied to one sideof a capacitor that is connected in common is changed, a change of thepotential at the commonly connected capacitor is called a D/Bphenomenon. Thus, referring to FIG. 11, a variation of the potentialoccurs due to the D/B at a point P in both cases where an alternatingdriving voltage is applied to the driving capacitor (Cdrv) and analternating common voltage is applied to the common electrode capacitor(Cvcom).

In the case where a touch occurs and Ct is formed, the voltage that iscaused due to the D/B by an alternating common voltage is represented byfollowing Equation 5.

$\begin{matrix}{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{VcomH} - {VcomL}} \right)\;\frac{Cvcom}{{Cdrv} + {Cvcom} + {Cp} + {Ct}}}}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

In Equation 5, ΔVsensor is the driving voltage that is caused due to theD/B in the touch detector 14, Vpre is the potential of the capacitorsthat are commonly connected immediately before the D/B voltage due tothe alternating of the common voltage is generated, VcomH is thehigh-level voltage of the common voltage applied to the common electrodecapacitor (Cvcom), VcomL is the low-level voltage of the common voltageapplied to the common electrode capacitor (Cvcom), Cdrv is the drivingcapacitance, Cvcom is the common electrode capacitance, Cp is theparasitic capacitance, and Ct is the touch capacitance.

In Equation 5, assuming that VcomH-VcomL is 10 V, and

$\frac{Cvcom}{{Cdrv} + {Cvcom} + {Cp} + {Ct}}$is 0.05, the voltage in the area {circle around (8)}, that is, Vpre is 3V. Thus, 3 V−10*0.05 V=2.5 V, and so the voltage of the area {circlearound (9)} is 2.5 V. Also, since the voltage drop due to Vdrv that isthe driving voltage in the area {circle around (10)} is 2 V, thepotential is lowered from 2.5 V to 0.5 V.

On the one hand, Equation 5 is a voltage detection equation according tothe alternating of the common voltage in the case that a touch hasoccurred. On the other hand, in the case that a touch has not occurred,there is no Ct in denominator of Equation 5, which will be expressed byEquation 6.

$\begin{matrix}{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{VcomH} - {VcomL}} \right)\;\frac{Cvcom}{{Cdrv} + {Cvcom} + {Cp}}}}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

In Equation 6, ΔVsensor is the driving voltage that is caused due to theD/B in the touch detector 14, Vpre is the potential of the capacitorsthat are commonly connected immediately before the D/B voltage due tothe alternating of the common voltage is generated, VcomH is thehigh-level voltage of the common voltage applied to the common electrodecapacitor (Cvcom), VcomL is the low-level voltage of the common voltageapplied to the common electrode capacitor (Cvcom), Cdrv is the drivingcapacitance, Cvcom is the common electrode capacitance, Cp is theparasitic capacitance, and Ct is the touch capacitance.

On the other hand, referring to Equations 5 and 6, it is possible todetect the voltage due to the D/B by applying an alternating drivingvoltage to the driving capacitor (Cdrv), but it is possible to detect achange in the voltage that is caused by the D/B phenomenon when thealternating common voltage is applied to the common capacitor electrode(Cvcom) of the display device, to thus detect a touch. In thisembodiment, in order to detect a larger voltage, that is, in order toincrease a detection sensitivity, it is better to remove the Cdrv termfrom the denominators of Equations 5 and 6. Since Cdrv can be formedwithin the TDI 30, it is possible to eliminate Cdrv in order to detectthe D/B voltage due to the alternating of the common voltage. If aswitching device such as a CMOS or TFT switch is connected to one sideof Cdrv and then the switching device turned on or off, in order toremove Cdrv, it is possible to determine whether or not Cdrv isconnected to the touch detector.

The following Equations 7 and 8 are used to calculate the drivingvoltages when Cdrv is removed and the voltage due to the D/B by thealternating of the common voltage is detected.

$\begin{matrix}{\mspace{20mu}{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{VcomH} - {VcomL}} \right)\;\frac{Cvcom}{{Cvcom} + {Cp}}}}}} & {{Equation}\mspace{14mu} 7} \\{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{VcomH} - {VcomL}} \right)\;\frac{Cvcom}{{Cvcom} + {Cp} + {Ct}}}}} & {{Equation}\mspace{14mu} 8}\end{matrix}$

Equation 7 is an equation of calculating the driving voltage when notouch occurs, and Equation 8 is an equation of calculating the drivingvoltage when a touch occurs.

Equations 5 to 8 are applicable to both cases where the touch screenpanel 50 is mounted on the upper surface the display device 200 as shownin FIG. 12, and where the touch screen panel 50 is patterned directly onthe color filter or the TFT substrate of the display device, as shown inFIG. 13.

Embodiment in an Area where a Common Voltage does not Alternate

By way of areas {circle around (11)} to {circle around (15)} as anexample, an embodiment of a case where a common alternating voltage doesnot alternate will be described as follows.

A display device using an LCD employing dot inversion is a displaydevice in which a common voltage that is applied to a common electrodeis a DC level, and a display device using an AMOLED or PDP is a displaydevice including no common electrode or having no alternating commonvoltage. In the embodiments of such cases, if a touch screen panel 50 iscoupled with a display device as shown in FIG. 12 or 13, the touchdetector 14 has no need to consider the driving voltage variation by thecommon voltage according to Equation 5 or 6, and a complex process ofdetecting a common voltage may be omitted as a unit of detecting a touchby avoiding the rising edge or the falling edge of the common voltage.

Areas {circle around (11)} and {circle around (14)} of FIG. 16 areintervals at which capacitors are charged into the pre-charging voltage(Vpre) by the charging unit 12 and the charged voltage is maintained inthe capacitors when the charging unit 12 is turned off. In addition,areas {circle around (12)} and {circle around (15)} of FIG. 16 areintervals at which the voltage due to the D/B is formed by the drivingvoltage (Vdrv), and thus it is confirmed whether or not a touch occursby considering the magnitude of the voltage. In this embodiment,assuming no touch has occurred, the voltage in the area {circle around(12)} is detected to be 4 V. An area {circle around (13)} is an intervalat which a voltage drop of 2 V occurs and thus the potential is kept as2 V, when the driving voltage is changed from high to low.

Even in the case that the common voltage of the DC level is applied tothe common electrode, an alternating voltage may be generated in thecommon electrode due to the noise generated during the driving of theswitching device (for example, a TFT switch of a TFT substrate of theLCD) or the liquid crystal in the display device. Typically, ITO (IndiumTin Oxide) is used as the common electrode and the sheet resistance ofITO is several hundred ohms or so. Thus, when the ITO common electrodeis used in a large-area display device of 7 inches or 10 inches, theresistance increases at a place further away from an applying unit towhich the common voltage of the DC level is applied, and the magnitudeof the common voltage at the place further away from the applying unitmay vary. This noise may be periodic and non-periodic noise. This noisemay correspond to VcomH and VcomL in Equation 5 or 6. That is, assumingthe noise alternates from −1 V to 2 V, VcomH is 2 V and VcomL is −1V.

In the case that the size of the alternating voltage of this noise issmall, changes in the magnitude of the voltage according to Equation 5or 6 are small, and thus the D/B voltage due to the driving of thedriving capacitor (Cdrv) is not affected, but if the alternating voltageof noise is big, the D/B voltage due to the driving of the drivingcapacitor (Cdrv) is affected. As a result, a touch signal should bedetected while avoiding such noise. Thus, in the same manner as thecommon voltage, the rising edge or the falling edge of such noise isdetected and then the touch signal should be detected while avoiding theedges of the noise.

In the case that the alternating common voltage exists in the embodimentof FIG. 16, the touch signal should be detected in synchronization withthe common voltage, and the touch coordinate is calculated. A reporttime of reporting the touch coordinate to a CPU of a set in use, forexample, a CPU of a mobile phone or a central processor such as A4 ofiPad® is determined in synchronization with the alternating cycle of thecommon voltage. However, in the case that there is no alternating commonvoltage, a touch signal cannot be detected in synchronism with thecommon voltage and thus the touch signal should be detected by setting adetection interval.

In FIG. 16, t10 is a period for detecting the touch signal in theabsence of the alternating common voltage. This period may have a timeduration from several μs to several ms, and a touch signal is reportedto a CPU of a set in synchronism with the period.

On the other hand, if distortion of a signal occurs due to the commonvoltage as in the case of the boundary area of the areas {circle around(8)} and {circle around (9)}, at the time of detecting the touch signalin areas {circle around (2)}, {circle around (5)}, and {circle around(8)} that are intervals of detecting the touch signal, the touchdetector 14 may perform a touch operation by considering the signaldistortion. However, the touch detector 14 may not easily performdetection of a touch due to the D/B voltage by the common voltage underthe circumstances that the magnitude of the alternating common voltageis non-continuous or unpredictable. Thus, if a touch is detected in aninterval at which the common voltage has a flat DC level by avoiding therising edge or the falling edge of the common voltage, it is possible tocircumvent this problem.

Thus, according to the embodiment of the present invention, timing of atouch detection is dynamically determined by performing synchronizationwith the common voltage based on the characteristics of the commonvoltage, to thereby perform the touch detection. Hereinafter, anembodiment for detecting a common voltage will be described below indetail.

FIG. 17 shows a common voltage detection circuit for detecting a commonvoltage according to an embodiment of the present invention. Referringto FIG. 17, a method of detecting edge portions of the common voltagewill be described as follows.

FIG. 17 shows the embodiment in which the common electrode capacitor(Cvcom) formed between the touch pad 10 and the common electrode 220 isFIG. 12 or 13 is formed in a common voltage detector 15.

As described earlier, if a plurality of the touch pads 10 of FIG. 12 or13 are used to form the touch screen panel 50, the parasitic capacitorsCp is formed between the sensor signal wires 22, and may also be formedin the process of assembling the TDI and the touch screen panel. Thus,Cp should be considered in the common voltage detection circuit.

In order to detect the edges of the common voltage, it is necessary tomake the common electrode capacitor (Cvcom) be in the Hi-z state. Forthis purpose, the charging unit 12 that may be made in the Hi-z state ata time of a turn-off operation and the common voltage detector 15 whoseinput is in the Hi-z state are needed. An upper reference level(hereinafter, abbreviated as URL) and a lower reference level(hereinafter, abbreviated as LRL) are supplied to the common voltagedetector 15, and these reference levels may be generated in the insideof the TDI or may be supplied to the TDI from outside of the TDI.

For the convenience of setting such LRL and URL, or in order to make theoutput waveform of the detected Vcom included within the scope of theoperating breakdown voltage of TDI, it is preferable that capacitorsconnected to Cvcom and Cvcom be also charged with an appropriate DClevel.

FIG. 18 is a waveform diagram of the common voltage detected by a commonvoltage detection circuit. Referring to FIG. 18, the waveform of RealVcom at the top of FIG. 18 is the actual Vcom that is applied to thecommon electrode 22 in FIG. 12 or 13. In this embodiment, assuming thatVcom alternates from 0 V to 5 V, and the charging voltage Vpre_com is2.5 V, since the charging voltage of 2.5V is charged in Cvcom and Cp, atthe state that charging unit 12 is turned on, the potential at the pointP is 2.5 V.

The common voltage is detected in two stages. The area 1 of FIG. 18 is apoint in time when the common voltage has not been still detected. Thisis a moment when the common voltage is not generated immediately afterthe power is on or during performing the process of detecting the commonvoltage and detecting the subsequent common voltage in synchronism withthe detected common voltage.

At a point in time when the common voltage has not still detected as inan area 1, the charge unit 12 is made to be turned on, to then apply thecharging voltage Vpre_com to Cvcom and Cp, and the charge unit 12 ismade to be turned off, to then wait until the rising edge or fallingedge of the common voltage is detected. Since Cvcom is in the Hi-z stateif the charging unit is turned off, a voltage difference is generatedaccording to Equation 7 when the rising edge or falling edge of thevoltage is applied to the common electrode 220 of FIG. 12 or 13.

Assuming that ΔVsensor detected in Equation 7 is 2 V, in the case of therising edge of the common voltage, the potential at the point P of FIG.17 is 4.5 V, and in the case of the falling edge of the common voltage,the potential at the point P of FIG. 17 is 0.5 V. Thus, in the case thatthe waveform of Real Vcom is a rising edge as in the area 1, detectedVcom is 4.5 V.

Since a value of

$\frac{Cvcom}{{Cvcom} + {Cp}}$in Equation 7 is a value that is predictable in advance, it is alsopossible to predict the value of ΔVsensor to some degree. Assuming thata value of

$\frac{Cvcom}{{Cvcom} + {Cp}}$is predicted as about 2 V, the value of ΔVsensor may alternate or swingbetween 4.5 V and 0.5 V by the Vpre_com. In this case, when the detectedcommon voltage is higher than the charging voltage of 2.5 V, it may bedetermined that the current common voltage is in the rising edge state.In contrast, when the detected common voltage is lower than the chargingvoltage of 2.5 V, it may be determined that the current common voltageis in the falling edge state.

Referring to FIG. 18, URL was set at 3 V and LRL was set at 2 V. In theembodiment of FIG. 18, the URL is a reference voltage for detecting therising edge, and thus a voltage that is higher than the URL may bedetermined as a rising edge. In the embodiment of FIG. 18, the URL isonly one example, and thus all the voltages that are larger than 2.5 Vand lower than 4.5 V may be set to URL. In the embodiment of FIG. 18,LRL is set to 2 V and the common voltage that is lower than the LRL maybe determined as a falling edge. A voltage between 2.5 V to 0.5 V can bearbitrarily set to LRL.

Referring to Equation 7, the D/B voltage detected by the alternating ofthe common voltage depends on the size of the charging voltage.Accordingly, the size of the charging voltage should be necessarilyconsidered in order to set the URL and LRL.

Once the common voltage is detected, the subsequent common voltageshould be detected in synchronism with the detected common voltage. Thisis because, since the common voltage usually repeats high and lowperiodically in the case that an alternating common voltage is generatedin the display device, it is predictable when the next common voltagehaving a polarity opposite to that of the detected common voltage willbe detected if the common voltage has been detected in any state. Forexample, assuming that the alternating cycle of the common voltage is 30μs, it is predicted that a falling edge will be detected and a low statewill be maintained 30 μs after the common voltage maintaining the highstate has been detected after the rising edge. Thus, if the state of thedetected common voltage, that is, a high state or a low state is found,the state of the next common voltage to be detected can be predictedwithin a set time. Thus, if the common voltage is not detected withinthe set time, this is because a common voltage detection system isabnormal, or the common voltage is not generated. Accordingly, it ispossible to perform an appropriate exception handling process.

An area 2 in FIG. 18 illustrates a process of detecting the next commonvoltage in synchronization with the detected common voltage. If it isassumed that Vg_com applied to the ON/OFF control terminal of thecharging unit 12 of FIG. 17 continues the low state in the area 2, theoutput unit of the charging unit 12 is in the Hi-z state and thus thepotential of the detected common voltage will continue to maintain at4.5 V (however, a potential change caused by the discharge has beenignored). In this state, the charging unit 12 is turned on (here,Vgcom_on determines a turn-on time.) and thus a charging voltage ofVpre_com is supplied to Cvom and Cp, the common voltage will continue tomaintain at 2.5 V from the charged time to a time even after thecharging unit is turned off. “Wait_vgcom” that is a time at which acharging voltage for detecting of the next common voltage after thecommon voltage has been detected is applied may be a time that can bearbitrarily set, and it is possible to set a desired time by using aregister for setting the “Wait_vgcom.” For example, if the period of thecommon voltage is 30 μs, “Wait_vgcom” is a time that can be changedwithin 30 μs. It is possible to freely set “Wait_vgcom” as 1 μs, 5 μs,10 μs, etc.

Thus, it is possible to remove noise that may occur in the commonvoltage by setting “Wait_vgcom” to a desired position. For example,assuming the period of the common voltage is 30 μs, if “Wait_vgcom” thatdetermines a turn-on time of the charging unit 12 is set to 1 μs, and“Vgcom_on” is set to 25 μs, the potential of the point P in FIG. 17 is2.5 V for at least 27 μs long, and fluctuation of the voltage due to thenoise that is caused by the application of the charging voltage does notoccur. Accordingly, a probability of malfunction due to noise may dropgreatly.

In the embodiment of FIG. 18, the cycles of the high section and the lowsection of the common voltage are different from each other. Thus, it ispreferable that “Wait_vgcom” can be set separately in the intervalswhere the common voltage is high and low. If the register is used to setthe intervals of “Wait_vgcom,” “Wait_vgcom_hi” is a value that is set inthe interval where the common voltage is high, and “Wait_vgcom_lo” is avalue that is set in the interval where the common voltage is low.

Thus, according to the embodiment of the present invention, the commonvoltage whose high and low intervals are different in their lengths canbe detected efficiently.

An area 3 is an interval at which the common voltage remains low sincethe falling edge. In the area 3, the common voltage is detected, Cvcomis charged after “Wait_vgcom” to then wait for the detection of thecommon voltage. Here, the potential is 2.5 V, and the potential of thedetected common voltage due to the D/B phenomenon by the falling edge ofthe common voltage becomes 0.5 V. Since the potential of the detectedcommon voltage of 0.5 V is lower than the LRL of 2 V, the common voltagedetector 15 detects the potential of the detected common voltage of 0.5V to thus output that the falling edge has been detected. This is outputthrough “detection result” of FIG. 18 and the TDI 30 uses the signaloutput through “detection result” of FIG. 18 to generate a signalrequired for the touch detection which will be described later, or togenerate a signal required for detection of the next common voltage. The“detection result” is output to the outside of the TDI. The “detectionresult” can be used in order to accurately see the high or low level ofthe detected common voltage, or in order to accurately measure the timeof the high or low interval.

FIG. 19 shows a common voltage detection circuit for detecting a commonvoltage according to an embodiment of the present invention. Referringto FIG. 19, the common voltage may be detected in the common voltagedetection circuit, or can be supplied from an external source that islocated in the outside of the TDI 30. The TDI 30 has a unit fordetermining whether the common voltage is detected in the inside of theTDI or whether an external common voltage is used. By setting the commonvoltage determination unit, a switching device 16 determines whether touse an externally applied common voltage or whether to use a commonvoltage detected by the common voltage detector 15.

A comparator unit 19 is used in the common voltage detector 15. Thecomparator unit 19 includes a comparator 19 a for detecting the risingedge of the common voltage, and a comparator 19 b for detecting thefalling edge of the common voltage. The comparator 19 a uses URL as thereference voltage and the comparator 19 b uses LRL as the referencevoltage. The comparator 19 a for detecting the rising edge of the commonvoltage outputs high or low when the detected common voltage is higherthan the URL, and the comparator 19 b for detecting the falling edge ofthe common voltage outputs high or low when the detected common voltageis lower than the LRL.

On the other hand, referring to FIGS. 12, 13 and 19, the touch pad 10for touch detection detects the common voltage as well as the touch.Accordingly, it is assumed that the touch occurs at the moment when thecommon voltage is detected, it is impossible to detect the commonvoltage by using Equation 7, and thus the common voltage should bedetected by using Equation 8. When Equation 8 is used, the size of thehigh and low section of the common voltage detected due to the additionof Ct in the denominator of Equation 8 may vary in contrast to theabsence of Ct. However, in the case that such a variation is not large,it is possible to detect the common voltage by changing the level of theURL and LRL. In the case that the high voltage or low voltage of thedetected common voltage lacks discrimination due to Ct, to accordinglymake it difficult to use it or induce noise, it is possible to detectthe common voltage by using the touch pad 10 where no touch occurs.Although it will be described later, several dozens or hundreds of touchpads 10 are used in the touch screen panel 50. Thus, it is possible toselect the touch pad where no touch occurs by making several touch padsconnected to the common voltage detecting circuit by using a multiplexer(hereinafter, abbreviated as Mux).

The input portion connected to the point P in common voltage detectionunit 15 of FIG. 17 or 19, should be in the Hi-z state. For this purpose,a device having a Hi-z input for connection with a buffer or gate may beconnected at point P. In addition, the level of a common voltage isdetected by using an ADC and the detected common voltage level istransferred to an internal CPU in the inside of the TDI (not shown) oran external CPU in the outside of the TDI, to thus be compared with anURL or LRL that is set in advance and to thereby detect the edges andlevels of the common voltage. Although it is not shown in the drawings,the common voltage detector 15 may use a filter in which a LPF (Low PassFiler) HPF (High Pass Filter), ranking filter or GCF may be used as thefilter.

In the case that a display device includes an LCD, no common voltage isgenerated in the back porch or front porch interval of the image frame.Otherwise, a change in the common voltage whose period is longer orshorter may occur. Alternatively, the common voltage may not be detectedor a detection error may occur due to an abnormal operation of thecommon voltage detector 15 and the noise superposed on to the commonvoltage. Even when such a problem occurs, the operation of the touchdetection circuit and the touch detection for detecting the touch shouldcontinue, and thus measures for the common voltage detection errors isneeded.

Measures for Common Voltage Detection Errors

1) Factory Calibration

Factory Calibration (hereinafter, abbreviated as fac.cal) is a method ofcontinuously performing touch detection in which a common voltage isdetected in a stable environment at the time of being shipped from afactory, factors regarding the detected common voltage are stored in amemory, and the touch detection is continued by using the data stored inthe memory when the common voltage is not detected. The factorsregarding the common voltage includes a duration of the high section ofthe common voltage, a duration of the low section of the common voltage,each duration of the high section and low section of the common voltagein the back porch or front porch interval of the image frame, and thelike. In the process of detecting the common voltage after factorycalibration has been completed and various factors of the common voltageare stored in the memory, an exception handling process depending on afailure mode of the common voltage is as follows.

(1) In the Case that a Common Voltage is not Detected

As described above, a time that will be taken until the appearance of anext common voltage since the common voltage has been detected can beseen schematically by calculation. A correct time may be measured byusing the output for the external monitor of the common voltageconnected to the exterior of the TDI. Therefore, if the common voltageis not detected at the expected time, a CPU 40 or a signal processor 35of the TDI that will be described later extracts the duration of themissed common voltage among the common voltage factors stored in thememory, and detects the touch signal in synchronization with theextracted duration.

For example, the common voltage of the low section has been detected andthen the common voltage of the high section should be detected after 30μs. Here, the time of 30 μs is a value that is detected in the processof fac.cal and stored in the memory. Thus, if the rising edge of thecommon voltage is not detected even with a waiting of 30 μs, the CPU 40generates a virtual starting point of the rising edge and generates asignal necessary to detect the next common voltage in synchronizationwith the virtual starting point of the rising edge, and also generatessignals required for the touch detection. The signals required for thetouch detection include the charge time using the charging unit 12 shownin the embodiment of FIG. 11, the adjustment of the time at which thedriving voltage is applied after the charge time, the setting of thetime at which the touch detection starts, etc., which will be describedlater.

(2) When an Error Occurs in the Detected Common Voltage

FIG. 20 is a waveform diagram illustrating a method of recovering anerror when the error occurs at the time of detecting a common voltageaccording to an embodiment of the present invention. Referring to FIG.20, the detected common voltage 1 (detected Vcom1) that is detected incontrast to the value stored in the memory represents early occurrenceof the detected common voltage, and the detected common voltage 2(detected Vcom2) that is detected in contrast to the value stored in thememory represents late occurrence of the detected common voltage. One ofthe methods of recovering a detection error, is embodied by setting awindow based on the value stored in the memory. For example, in the casethat the duration of the high section of the common voltage stored inthe memory is 30 μs, the detection time should become from 30±5 μs inorder to set a window of 5 μs. Accordingly, the common voltage that hasbeen detected within a range of 25 μs to 35 μs is considered normal andthus the common voltage detected beyond the range of 25 μs to 35 μs istreated as badness. Here, the window can be set arbitrarily and the TDI30 has a unit of setting the window. For example, a window should be setthrough a register or should be written in a certain area of anon-volatile memory such as a flash memory.

The common voltage that is detected earlier than the window in the samemanner as that of the detected common voltage 1 (detected Vcom1) isconsidered as noise and is ignored. If the common voltage is notdetected even at the end of the time window, at 35 μs, the CPU recallsthe duration of the low-level common voltage among the factors writtenin the memory, and generates a signal for detecting the next commonvoltage in synchronization with the recalled duration of the low-levelcommon voltage, and also generates a touch signal for detecting a touchinput. For example, assuming the duration of the low section is 25 μs, 5μs has already passed and thus the necessary signals are generated insynchronism with 20 μs. In addition, if a common voltage is not detectedduring 35 μs that is obtained by adding 30 μs written in the memory and5 μs that is the window area in the same manner as that of the detectedcommon voltage 2 (detected Vcom2), the CPU generates a virtual commonvoltage of 20 μs as described above, and generates signals required insynchronization with the virtual common voltage.

The embodiment of the present invention having the above-describedconfiguration, performs common voltage synchronization dynamicallycorresponding to the non-detection or detection error of the commonvoltage, by using the common voltage information and the windowinformation pre-stored in the process of fac.cal.

2) Real-Time Calibration (Abbreviated as RTC)

In the case that a display unit is med of a LCD (Liquid CrystalDisplay), a LCD Drive IC (hereinafter, abbreviated as LDI) generates acommon voltage. LDI is an IC (Integrated Circuit) of playing a role ofapplying a pixel voltage to a TFT (Thin Film Transistor) of a LCD andcontrolling the gate timing of the TFT. In order to generate a commonvoltage from the LCD, an oscillator (hereinafter, abbreviated as OSC) isused, and the OSC has a variable period since values of a resistor and acapacitor constituting the OSC are changed depending upon a change intemperature. If the common voltage is detected by referring to only thefactors stored in the process of fac.cal in the case of a big change, anerror may occur at the time of an exception handling process that istreated in the case that the common voltage is set in the outside of thewindow area. In order to avoid such a problem, the factors of the commonvoltage detected in real time, are stored in the memory and the storedfactors of the common voltage are used for the exception handlingprocess, which is called RTC.

In addition, without performing fac.cal, there is a method of storingfactors extracted from RTC in a memory and using the stored factors inan exception handling process.

Since fac.cal, a separate memory area is required for RTC, and a unitfor determining whether the factors stored in the process of fac.cal areused or the factors detected from RTC are used in order to perform theexception handling process should be provided. It is reasonable to usethe RTC factors. However, since the RTC factors have the probability ofoccurrence of detection errors due to noise higher than the detectionerror occurrence probability of the fac.cal factors, it may be necessaryto use the fac.cal factors as absolute standards. Accordingly, it isnecessary to provide a unit for selecting either the RTC factors or thefac.cal factors. Such a unit for selecting either the RTC factors or thefac.cal factors may be determined by changing a register that is set inthe inside of the TDI or storing the RTC factors and the fac.cal factorsin the non-volatile memory, and referring to the changed register orstored factors.

FIG. 21 is a flow chart for performing a fac.cal process for extractionof factors of a common voltage. Referring to FIG. 21, a first step forthe fac.cal process for extraction of factors of a common voltage is astep of determining whether the common voltage is detected. As describedabove, since the common voltage has the DC level in the case of a dotinversion LCD, it is not necessary to detect the common voltage. Thus, aunit for determining whether the common voltage is detected or notshould be provided in the inside of the TDI. Such a unit may beimplemented by using a register or a non-volatile memory.

In the case of detecting the common voltage, the signals illustrated inFIG. 16 are generated, and thus the common voltage detection circuitshown in FIG. 17 or 19 is provided to perform the common voltagedetection step.

Referring back to FIG. 21, once the common voltage detection iscompleted, a step of storing the common voltage factors detected in thecommon voltage detector 15 in the memory, is performed.

Assuming that the absolute time required for detecting the touch signaland calculating the detected signal is 40 μs, it is impossible to detectthe touch signal while avoiding the rising edge or the falling edge ofthe common voltage in synchronization with the common voltage duringperforming the touch detection in the case that the duration of thecommon voltage is less than 40 μs. Likewise, in the case that the dutyof the common voltage is less than the time required for the operationof the touch signal, the duties of a plurality of the common voltagesmay be used. For example, assuming that each of the durations of thehigh and low sections of the common voltage is 30 μs and the timerequired for the touch signal operation is 40 μs, the touch detector 14detects the rising edge and falling edge of common voltage and outputsonly one signal, to thus calculate a touch signal in synchronism withonly the one output signal. Otherwise, the TDI 30 may generate signalsnecessary for the touch signal operation in synchronism with one of thetwo detected voltage signals.

In the case that duration of the common voltage is too long, the timerequired for the touch signal operation may be consumed a plurality oftimes in some cases. For example, duration of the common voltage is 100μs, and the time required the touch operation is 40 μs. In such cases, aplurality of times of touch operations are performed in a commonvoltage, and thus the report time taken for reporting the touchcoordinates to a set can be even faster, which will be a unit for makinga reaction rate faster. Likewise, a unit for determining whether asingle touch signal operation for a plurality of common voltages will beperformed or whether a plurality of times of touch signal operationswithin a period of a common voltage will be performed, should beprovided in the TDI 30, which may be implemented as registers or memory.

By the above configuration, timing of the effective touch detectionoperation may be determined on the basis of duration of the commonvoltage and the time necessary for the touch operation.

The voltages due to the D/B that is induced during detection of therising edge or the falling edge of the common voltage are expressed asEquations 7 and 8, and these signals affect the voltages detected by thedriving voltages that are expressed as Equations 1 and 2, and areapplied to the driving capacitor. Accordingly, the voltage due to theD/B phenomenon that is the touch signal should be detected whileavoiding a point in time where the rising edge or the falling edge ofthe common voltage occurs.

The distortion of the voltage by Equation 7 or 8 using the commonvoltage at the state where the detection has been completed by usingEquation 1 or 2, the “Vpre_com” term in Equation 7 or 8 becomes ΔVsensorthat is a voltage detected in Equation 1 or 2. That is, when the commonvoltage alternates after the voltage has been detected according toEquation 1 or 2 representing the D/B voltage detection method using thedriving capacitor (the point P is still in the Hi-z state), the voltageby Equation 7 or 8 is detected. Here, the “Vpre_com” term of Equation 7or 8 means the voltage detected by Equation 1 or 2. This embodiment hasbeen described in the embodiment of the areas {circle around (8)} and{circle around (9)} of FIG. 16. Accordingly, in order to preventdistortion of the touch signal that may occur at the rising edge or thefalling edge of the common voltage, or that may occur due to noiseoccurring in the common voltage, the touch signal should be detectedwhile avoiding an inflection point at which the size of the signalchanges.

FIG. 22 is a waveform diagram illustrating a method of detecting thetouch signal in synchronization with the detected common voltageaccording to an embodiment of the present invention. Referring to FIG.22, the “detected common voltage” is a common voltage detected by thecommon voltage detector 15 in the embodiment of FIG. 17. In FIG. 22,“Vg” is a voltage applied to the ON/OFF control terminal of the chargingunit 12 in the embodiment of FIG. 11, in which a switching device thatis used as the charging unit 12 in a high state, is turned on, and theswitching device that is used as the charging unit 12 in a low state isturned off. In FIG. 22, “Sel_pretime” determines the high section timeof Vg. In FIG. 22, “Vdrv” is a driving voltage applied to the drivingcapacitor (Cdrv) of FIG. 11. The time at which Vdrv becomes high insynchronization with the falling edge of Vg is defined as “sel_drvdly.”

In FIG. 22, the time t1 of the high section of the detected commonvoltage and the time t2 of the low section of the detected commonvoltage are different from each other, but both t1 and t2 may be same ort2 may be longer than t1.

In FIG. 22, an area 1 is an area for detecting the touch signal at therising edge of the common voltage and an area 2 is an area for detectingthe touch signal at the falling edge of the common voltage. Here, thetouch is detected while avoiding the edge portions of the common voltagedetected in the area 1 or 2. In order to detect the touch, the chargeunit 12 is first turned on, and thus the charging voltage is supplied toall capacitors connected to the point P of FIG. 11, to thus charge thecapacitors. Although it will be described later, several dozens of toseveral hundreds of touch pads 10 are connected with the TDI via thesensor signal wires 22 on the touch screen panel 50. Accordingly, as thelength of the sensor signal wires 22 becomes longer, the resistance isincreased. Thus, the charging time may vary depending upon the positionsof the touch pads 10 which are located on the touch screen panel 50.Thus, “sel_pretime” of FIG. 22 for determining the charging time thecharging unit 12, should be variable, which has a unit for varying thecharging time in the inside the TDI. For example, “sel_pretime” is avalue that can be selected within a range from 1 ns to 1000 ms, which isdetermined by the internal register in the inside of the TDI.

In one embodiment, 10 μs may be assigned in the ‘01’ register and 100 msmay be assigned in the ‘0A’ register. This is one embodiment ofassigning the registers. A variety of charging times are assigned intomore registers on a one-to-one correspondence basis.

According to the embodiment described above, the charging time may bevariably determined on the basis of the distance between the touch padsformed in a matrix form and the TDI 30, and thus it is possible todetect the touch accurately.

When the charging voltage is applied in the area 1 or 2, it ispreferable that the charging voltage should be applied while avoidingthe rising edge or falling edge of the common voltage that is a voltagetransform portion of the common voltage. This is because it ispreferable that the charging voltage should be applied after apredetermined time since the common voltage is detected, in order toprovide a method of avoiding noise that can be applied to a voltageinflection portion and can last to a degree in the case that a commonvoltage is actually detected in industrial applications, although thereis no noise ideally in the common voltage detected in the embodiment ofFIG. 22,

FIG. 23 is a waveform diagram illustrating an example of an actuallydetected common voltage. Since the initial parts of the rising edge andfalling edge of the common voltage are not linear, distortion occurs inthe touch signal in the case that the touch signal is detected innon-linear sections of the rising edge and falling edge of the commonvoltage. Thus, in order to avoid such non-linear sections, the chargingvoltage is applied to thus detect the touch signal after a specifiedtime of “sen_hi_dly” or “sen_lo_dly” has elapsed. “Sen_hi_dly” is adelay point in time that is synchronized with a point in time at whichthe common voltage higher than the URL is detected and “sen_lo_dly” is adelay point in time that is synchronized with a point in time at whichthe common voltage lower than the LRL is detected.

Here, the time for turning-on the charging voltage may be given in aportion of the non-linear section of the common voltage. This is becausefluctuation of the voltage due to D/B phenomenon by the alternatingcommon voltage does not occur if the charging is made in the non-linearsection of the common voltage, and fluctuation of the voltage due to thecommon voltage does not occur if the linear section of the commonvoltage is output at the point in time when the charging has beencompleted.

Referring back to FIG. 23, duration of the non-linear section at thehigh section of the common voltage and duration of the non-linearsection at the low section of the common voltage differ from each other.In order to avoid non-linear sections differing from each other in thehigh and low sections of the common voltage, it is necessary to makesetting of “sen_hi_dly” that is the time to avoid the high section andsetting of “sen_lo_dly” that is the time to avoid the low section differfrom each other. The TDI 30 has a unit for setting two pieces of thetime and, in one embodiment, may be determined by means of suchregisters within the TDI.

Referring again to FIG. 22, a signal for detecting a touch signal insynchronization with the falling edge of the common voltage is generatedin an area 2. When the common voltage is changed from high to low, thetime to avoid the low section is delayed for a certain time and isexpressed by “sen_lo_dly.” Meanwhile, the driving voltage “Vdrv” in FIG.22 is changed from low to high in synchronization with the point in timeat which the charging unit 12 is turned off after the potential of thepoint P of FIG. 11 is formed into the charging voltage since thecharging unit 12 is turned on. The process of detecting the touch signalby using Equation 1 or 2 by the change of the state is the same asdescribed above.

In an embodiment of the present invention, the case of detecting thevoltage variation occurring when Vdrv is changed from low to high hasbeen described as an example. This is only one embodiment, andalternatively a touch signal can be detected even when Vdrv is changedfrom high to low. In addition, a synchronization point in time at whichthe level of Vdrv is changed may be the common voltage, or a point intime of turning on the charging unit 12.

In FIG. 22, if the time for applying Vdrv becomes longer after thecompletion of charging, noise may be input during waiting the input ofVdrv, to thus change the potential of the point P in FIG. 11. Tocircumvent this, it is necessary to quickly apply the driving voltage(Vdrv), but Vdrv should be applied after the switching device used inthe charging unit 12 has been completely turned off, and thus the timeat which Vdrv is applied is made to be variable to thereby find out anappropriate time for tests. Thus, the TDI 30 has a unit for varying atime at which Vdrv is applied. In one embodiment, the Vdrv applying timemay be selected in a range of 1 ns to 100 ms in synchronization with thechange in the voltage level of Vg when the charging unit is turned offby the change in the voltage level of Vg that is the control voltageinput to the ON/OFF control terminal of the charging unit 12. A registercan be used as an example of a unit for the Vdrv applying time, in whichthe first value of the register is 1 ns and the last value thereof is100 ms.

In addition, as described above, the point in time at which Vdrv isapplied may be synchronized with the high or low of Vg, but may also bethe transform portion of the common voltage, and Vdrv may be alsoapplied by a timer of the TDI or an interrupt.

When the driving voltage (Vdrv) is applied, the voltage du to the D/B isformed and is detected by the touch detector 14. Here, as describedabove, the resistance values of the sensor signal wires 22 vary by theposition of the touch screen panel 50, and thus the time at which thevoltage due to the D/B when Vdrv is applied is formed appearsdifferently according to the resistance value formed by the sensorsignal wires 22. For example, the touch pad 10 that is located thefarthest away from the TDI has a resistance value of several hundreds ofKohm and the touch pad 10 adjacent to the TDI has a resistance value ofseveral tens of Kohm. This is because the resistance value of severalhundreds of Kohm is derived by calculation, when the sensor signal wires22 of the line width of about 50 μm are formed at a distance by 9 cm,that is, the farthest away from the touch screen panel 50 that is usedin the seven-inch class display device, since the touch pad 10 includesa transparent conductor such as ITO or IZO, or CNT and the sheetresistance is approximately several hundred ohms or so, which will bedescribed later. As described above, since the point in time at whichthe change in voltage due to the D/B by resistance of the touch pad 10and the capacitor formed in the sensor signal wires 22 is completedvaries, the point in time at which the voltage is detected since Vdrv isapplied should be variable. Thus, the TDI has a unit for varying thetime at which the voltage is detected since Vdrv is applied.

“Start Detection” of FIG. 22 is illustrative of such a voltage detectionpoint in time, and has a variable width of around from 1 ns to 100 ms insynchronism with an inflection portion of the common voltage or Vg.Varying can be done by using registers in which a plurality of times aremapped to a plurality of registers on a one-to-one correspondence basis.

Meanwhile, referring to Equation 1 or 2, the voltage detected by the D/Bis in proportion to Vh−Vl, which is the voltage fluctuation width ofVdrv. The voltage detected when Vdrv is changed from 0 V to 2.5 V fallsdown to a 50% level, in comparison with the voltage detected when Vdrvis changed from 0 V to 5 V. Therefore, it is possible to adjust the sizeof the detection voltage by the D/B by properly adjusting the voltageamplitude of Vdrv. This action can be achieved by a power supplycontained in the TDI 30 or an external power supply that is providedfrom the outside of the TDI 30. When using the internal power supplycontained in the TDI 30, the size of Vdrv is changed by changing the setvalues of the registers contained in the TDI.

FIG. 24 is a table diagram illustrating an embodiment for changing thesize of Vdrv according to the setting of the registers contained in theTDI. Referring to FIG. 24, when selecting the 00h address of theregister, the voltage of Vdrv becomes 2 V and when selecting the 07haddress of the register, the voltage of Vdrv becomes 16 V.

As described above, the touch detecting device according to anembodiment of the present invention may vary the driving voltage (Vdrv),and may adjust the size of the detection voltage associated with thetouch sensitivity.

FIG. 25 is a circuit diagram illustrating a touch screen panel accordingto an embodiment of the present invention. FIG. 25 shows an embodimentapplying the touch detecting device of FIG. 10 or 11, in which touchpads 10 are arranged in a dot matrix form.

The configuration of the TDI 30 is illustrated at the bottom of FIG. 25.The TDI 30 includes a driving unit 31, a touch detector 14, a timingcontroller 33, a signal processor 35, a memory unit 28, a common voltagedetector 15, a power supply 47, and a communication unit 46, and mayfurther include a CPU 40. The CPU 40 is a microprocessor having anarithmetic function and may be located outside of the TDI 30.

The touch pads 10 and the sensor signal wires 22 are patterned andformed on the touch screen panel 50. The touch pad 10 is made of atransparent conductor such as ITO, IZO, or CNT (Carbon Nano Tube), andformed of a square, circle, triangle, star-shaped, or fractalconfiguration, but is not limited thereto. The touch pads 10 and thesensor signal wires 22 are formed of an identical material, that is,when the touch pads 10 are formed of ITO, the sensor signal wires 22 arealso formed of ITO. This enables the touch pads 10 and the sensor signalwires 22 to be patterned on one piece of a mask, and enables the touchscreen panel 50 according to the present invention to be fabricated intoa single layer with a single piece of a mask.

The touch screen panel 50 according to the present invention using thesingle layer does not make the touch pads 10 or the sensor signal wires22 pass across the upper or lower side of the other touch pads 10 or thesensor signal wires 22, to thereby reduce the thickness of the touchscreen panel 50, improve the transmittance, and improve yield, and tothus provide a cost savings effect.

FIGS. 26A through 26C show various configurations of the touch pads 10in accordance with the embodiments of the present invention. Referringto FIGS. 26A through 26C, FIG. 26A shows a pattern of triangles facingeach other, FIG. 26B shows a pattern of arrows matched to each other inshape, and FIG. 26C shows a pattern of crescent or half moon shapesmatched to each other in shape. These shapes enable the coordinates ofthe touch to be extracted by using the relationship of the areas of thetouch pads 10 c and 10 d when a plurality of the touch pads that areformed in oblique lines of FIG. 26A face each other.

For example, when a touch unit is located in the center of a squareformed by the touch pads 10 c and 10 d, information of the area obtainedby the touch pad 10 c is same as that obtained by the touch pad 10 d,and thus it can be seen that the touch unit is located at the center ofthe square. In addition, when the touch unit occupies 20% of the area ofthe touch pad 10 c and 80% of the area of the touch pad 10 d, it can beseen that the touch unit is located at the upper portion of the square,and is located below about 20% from the upper portion of the square.Thus, as shown in FIGS. 26B and 26C, in the case that the touch unitcontacts the plurality of touch pads 10 adjacent to the touch unit, itis possible to detect the position of the touch unit with an area ratioeach other. Combinations of the touch pads 10 having a cross-correlationas illustrated in FIGS. 26A through 26C are only examples, and may beimplemented in various forms, such as a star-shaped or leaf-shapedconfiguration.

FIG. 27 shows an example of a touch screen panel 50 is illustrated inFIG. 5 of Korean Patent Laid-open Publication No. 10-2010-0021112according to the prior art in contrast to the embodiment of the presentinvention. The example of FIG. 27 corresponds to the FIG. 26A embodimentof the present invention, in which according to the technique of FIG.27, the sensor signal wires 22 do not pass along the left and rightsides of the touch pads (522, 524, 526, and 528 of FIG. 27 and 10 c and10 d of FIG. 26A) but the sensor signal wires 540 are wired only on thetop and bottom of the touch screen panel, differently from the FIG. 26Aembodiment of the sensor signal wires 22 passing along the left andright sides of the touch pads. This technique narrows the width of theleft and right sides of the touch pads (522, 524, 526, and 528 of FIG.27 and 10 c and 10 d of FIG. 26A) to enable accurate detection of thetouch coordinates but to limit a number of the touch pads. On the otherhand, if the touch detection sensitivity is good, as shown in FIG. 26A,the sensor signal wires 22 are wired along the left or right sides ofthe touch pads 10. Although the gap between the touch pads is widened,the touch signal can be detected, and since a more number of touch padscan be also laid in comparison with the embodiment of FIG. 27, the touchcoordinates can be detected more precisely.

FIG. 28 shows the prior art compared with the other prior art, and is aschematic view showing a conventional wiring diagram of sensor signalwires 22 that are arranged on top and bottom of touch pads 10. Referringto FIG. 28, the sensor signal wires 22 of FIG. 28 are arranged at theupper and lower sides of the touch pads 10, in which the left-sidesensor signal wires 22 are gathered on the left side of the touch screenpanel and the right-side sensor signal wires 22 are gathered on theright side of the touch screen panel 50. This connection method hasdrawbacks of degrading marketability of products since the signal wiresgathered at the left and right of the touch screen panel 50 areincreased and thus the left and right areas of the touch screen panel 50are widened. In contrast, since the sensor signal wires 22 are notintegrated in the left and right of the touch screen panel 50, in theembodiment of FIG. 25, the left and right areas of the touch screenpanel 50 is narrowed, and thus the touch screen panel 50 can be formedof a narrow bezel type, to thus increase marketability.

On the other hand, in the case of the technique of FIG. 28, the signalwires originating from the touch pad located on the top of the layoutare connected with the TDI 30, and thus length of the wires becomeslonger considerably, to thus increase the resistance. Accordingly, it isimpossible to make the touch pads 10 and the sensor signal wires 22formed of a transparent conductor such as ITO. Thus, the sensor signalwires 22 disposed along the left or right of the touch screen panel 50are formed of a metal-based material such as copper (Cu) or silver (Ag).This means that a further process separated from a process of patterningthe touch pads 10 should be used, to thereby cause a production cost torise and the yield to be decreased.

Referring back to FIG. 25, as shown in the embodiment of FIG. 11, thedriving unit 31 has the charging unit 12 and the driving capacitor(Cdrv). Also, a common voltage detection circuit shown in FIG. 17 or 19is present in the driving unit 31. Referring to Equation 1 or 2, since adifference in the size of the voltage detected by the size of Cdrvoccurs, a unit for changing the size of Cdrv should be provided in theinside of the TDI. As Cdrv becomes large, the size of the detectionvoltage becomes large, which means that the detection sensitivity isgood. However, if Cdrv becomes too large, the volume of the TDI isincreased, which is a factor of causing a rise in price of the TDI. Cdrvshould be designed to have an appropriate size. In order to adjust thesize of Cdrv, registers for adjusting the size of Cdrv are provided inthe inside of the TDI. Each register has a plurality of addresses, inwhich respectively different Cdrv values are mapped to the respectiveaddresses. Cdrv corresponding to the selected register values isconnected to the touch signal detection circuit included in the touchdetector 14.

In the embodiment of FIG. 25, the touch pads 10 consist of 35 units oftouch pads of 5 (width)×7 (length), in which the touch pads 10 arelocated on top of the A/A area of the display device, and the A/A areais divided into 35 touch areas. This is just one example. 100 or moretouch pads 10 may be mounted on the actual touch screen panel 50. If thetouch detector 14 shown in FIG. 14 which corresponds to the so-may touchpads 10 on a one-to-one basis is present in the driving unit 31 of theTDI 30, the area of the TDI is widened to thereby cause a factor ofraising the prices. Therefore, a small type of the touch detector 14 isprovided in the driving unit 31, and the touch pads 10 are multiplexedin a time division manner to thus detect the touch signal.

For example, a touch detector 14 shown in FIG. 11 is provided in thedriving unit 31. The touch pads 10 are multiplexed in sequence one byone and are connected to the charging unit 12, the touch detector 14,and the touch signal detection circuit connected with the capacitorsconnected with the charging unit 12 and the touch detector 14. That is,the touch signal detection circuit is one, but the number of the touchpads 10 is 35, and so a multiplexer having 35 inputs and selecting oneof the 35 inputs to then connect the selected one input to the detectioncircuit should be designed.

In another embodiment, a driving unit 31 is provided with a plurality oftouch signal touch detectors 14. However, the plurality of touch signaltouch detectors 14 includes the number of the touch detectors less thanthe number of the touch pads 10. In the embodiment in FIG. 25, five orseven touch detectors 14 are provided. In the case of the five touchdetectors 14, the five touch detectors 14 correspond to five laterallyarranged touch pads 10 on a one-to-one correspondence basis, to thussimultaneously detect touch signals from the five touch pads 10.Therefore, it is possible to detect the touch signals from the 35 touchpads 10 by seven-times scanning operations. In addition, if the seventouch detectors 14 are used, it is possible to detect the touch signalsfrom the longitudinally partitioned seven touch pads 10 for one-timescan, and thus it is possible to detect the touch signals from the 35touch pads 10 for five-times longitudinal scanning operations.

The touch pads 10 are used for detecting the touch signals but are usedfor detecting the common voltages. For example, in FIG. 25, the firsttouch pad (hatched in FIG. 25) of the sixth line in the transversedirection, is connected to the common voltage detector to detect thecommon voltage, since the first touch pad of the sixth line is not stilla sequence of detecting the touch signal when the touch pads 10 includedin the first line to the fifth line detect the touch signals. When thefirst touch pad of the sixth line becomes a sequence of detecting thetouch signal since the touch detection has been completed up to thefifth line, the touch pad 10 with which the touch detection has beenalready completed or the touch pad 10 with which the touch detection hasnot been completed yet is used as the touch pad that detects the commonvoltage. A signal processor 35 controls the multiplexer (MUX) of thedriving unit to determine whether the touch pad 10 is connected to thetouch detector shown in FIG. 11 or the common voltage detector shown inFIG. 17, and to thus transfer necessary control signals to the drivingunit 31. The driving unit 31 makes the touch pad 10 connected to thetouch detector or the common voltage detector according to on the signalreceived from the signal processor 35. Here, one or a plurality ofcommon voltage detectors are used to detect the common voltage, in whicha plurality of respectively different touch pads 10 are connected to theplurality of common voltage detectors.

It is desirable to lower the resistance of the sensor signal wires 22originated from the touch pads 10 and connected to the TDI 30 as low aspossible. For this purpose, as shown in FIG. 25, the sensor signal wire22 is connected to the corner of the 5 o'clock position of each touchpad 10 so that a connection path between the touch pad 10 and the TDImay be the shortest distance. The 5 o'clock position of the touch pad 10provides a path of minimizing the connection path between the touch pad10 and the TDI. In the configuration of the touch pad 10 as shown inFIG. 25, when the TDI 30 is located on the upper side of the layout, thesensor signal wires 22 will be originated from near the corner partlocated in the 11 or 5 o'clock position of the touch pad 10 and will beconnected to the TDI 30.

Further, as the touch pad 10 is the farther away from the TDI 30, theresistance by the sensor signal wires 22 and the parasitic capacitancedetected by the sensor signal wires 22 become large. Accordingly, as thedistance becomes farther, the line widths of the sensor signal wires 22are widened, to reduce the size of resistance and the gaps between thesensor signal wires 22 are widened, to reduce Cp. That is, according toone embodiment of the present invention, the widths between the sensorsignal wires 22 are differently set on the basis of the distance betweenthe touch pads 10 and the TDI 30, to thereby prevent degradation of thetouch detection according to the positions of the touch pads 10.

As described above with reference to FIG. 11, the touch detector 14detects the voltage due to the D/B and amplifies the detected voltage tothen output the amplified result to the ADC converter 14-5 (hereinafter,shortly named as ADC). One or a plurality of ADCs 14-5 may be includedand used in the touch detector 14. As more ADCs 14-5 are used, it may beadvantageous to shorten the time that is taken to convert the detectedanalog signals into digital signals. However, as the number of ADCs 14-5is increased, the current consumption increases, and the area of the TDI30 is increased, to thereby cause the cost to rise. Thus, an appropriatenumber of ADCs should be selected considering a report time to a set.The DAC 14-3 is also included in the touch detector 14. The DAC 14-3plays a role of calibrating the voltage that is used as a referencesignal applied to a differential amplifier for the configuration of thedifferential amplifier that will be described later, and that isdetected in each of the touch pads 10.

The timing controller 33 plays a role of generating a plurality ofdifferent clock signals required by the TDI. For example, the clock isrequired in order to operate the CPU 40 of FIG. 25, or the clock is alsorequired in order to operate the ADC or sequentially operate themultiplexer in the driving unit 31. As described above, there are anumber of types of clock required for each function, and the timingcontroller 33 generates and provides a plurality of various types ofclock.

Since the common voltage detector 15 has been previously described, thedetailed description thereof will be omitted.

Referring back to FIG. 25, the signal processor 35 transfers the ADCvalue generated from the touch detector 14 to the CPU 40, or transfersthe ADC value to the outside of the TDI 30 through the I2C or SPI signalwire by controlling the communication unit 46, or generates and suppliessignals required by all internal functional devices or blocks such asthe signal processor 35 and the driving unit in the inside of the TDI30. The functional devices or blocks refer to respective functions thatare shown in FIG. 25. For example, there are nine (9) functional devicesor blocks inside the TDI in which the CPU 40 is one of them. The signalprocessor 35 stores the ADC value generated from the touch detector 14in the memory unit 28 and performs the required operations. For example,the signal processor 35 may calculate a touch area due to a touchoperation between the touch pad 10 and the contact unit with referenceto the ADC value generated by the touch detector 14, and also calculatethe coordinate of the touch by using the ADC value or the calculatedarea value. Referring to FIG. 14B, the touch is detected from thefifteen touch pads 10 by the finger 25, and the opposite area withrespect to the finger for each touch pad 10 is generated. Here, sincethe touch coordinate is the center of gravity of the area formed by thefifteen touch pads, the area and the touch coordinate have differentconcepts.

The memory unit 28 includes a flash memory, E2PROM, SRAM, DRAM, or thelike. The result values of fac.cal or register values, or programsnecessary to operate the CPU 40 are stored in the flash memory orE2PROM. In FIG. 25, a set of the touch pads 10 that are arranged in apattern of a 5×7 array is defined as a frame, and thus a memoryincluding detection voltage values of the touch pads 10 included in asingle frame may be called a frame memory. In order to sense the frame anumber of times, and detect the touch signal by using the average ofthese or a filter, a plurality of frame memories are needed. When thetouch signal is detected by using a 10-bit, 12-bit, or 14-bit ADC, thehigher resolution of the ADC may be, the more size of the frame memoryis increased. Accordingly, if an increment (that is a difference betweenthe first value and the second value) is stored on the basis of the datathat is initially detected and stored in the first frame memory, it willhelp to reduce the size of the memory.

On the other hand, the memory unit 28 may require a line memory. Forexample, in the embodiment of FIG. 25, in the case that the transverselypartitioned five touch pads 10 or the longitudinally partitioned seventouch pads 10 are detected at the same time, the line memory capable ofstoring five or seven touch signals is required. In order to attempt toobtain an average or use a filter by using touch data detected byscanning the lines a plurality of times, a plurality of line memoriesare required. Since such a line memory is smaller than a frame memory inview of capacity, it is more efficient for reducing the size of thememory, to use a line memory other than a frame memory.

The CPU 40 overlaps with the signal processor 35 with a lot of features.Therefore, the CPU 40 may not be included in the TDI 30 or may bepositioned outside of the TDI 30. In the case the CPU 40 and the signalprocessor 35 are concurrently used, it may be designed so that one ofthem may not be used.

The CPU may play a role of performing the most part of the signalprocessor 35, and for example may extract the touch coordinate, performgestures such as zoom, rotation, move, or the like, or perform variousfunctions. The functions may include “palm rejection” or a smart gripdescribed in FIG. 15. Furthermore, a zooming signal is generated or thestrength of the touch input is calculated, by calculating an area of thetouch input. In the case that a GUI object such as a keypad is touchedat the same time, data is processed in various forms in a manner thatuser's desired (e.g., the more detected area) GUI object is recognizedas only valid input, the processed data may be used in the TDI 30 or maybe transmitted to the outside via a communication cable.

A program for controlling the CPU 40 is installed in the memory unit 28,and can be replaced with a new program in the event of modifications.The new program is run by using a communication bus included in thecommunication unit 46, e.g., by using serial communications such as I2C,SPI, USB, or by using parallel communications such as CPU Interface(hereinafter I/F). The CPU 40 calls a plurality of the signal detectionvalues that stored in the line memory or the frame memory, to thusobtain an average value, or to extract a stable value by using a filter.The values stored in the memory are the ADC values or and the areavalues.

The communication unit 46 externally outputs the necessary informationto the outside of the TDI 30 or inputs the information provided from theoutside of the TDI into the inside of the TDI 30. The serialcommunications such as I2C or SPI or the parallel communications such asparallel I/F of CPU Interface is used for the communication unit.

As shown in FIGS. 10 and 11, the voltage at the point P is convertedinto the ADC value in the ADC converter 14-3 of the touch detector 14.Before being converted into ADC value in the ADC converter 14-3, it ispreferred that the voltage at the point P be amplified in the amplifier14-2.

Various forms of amplifiers such as an inverting amplifier,non-inverting amplifier, a differential amplifier, or an instrumentamplifier may be used as the amplifier. Referring to Equation 1 or 2, ameaning of detecting the touch signal is a meaning of detecting adifference between a result that is obtained by Equation 2 when Ct isadded in the denominator of Equation 2, and a result that is obtained byEquation 1 when Ct does not exist in the denominator of Equation 1. Forexample, it is assumed that Equation 1 is a constant value, and thisvalue is 4 V. Since Ct is added in the denominator of Equation 2, thevalue of Equation 2 may not be greater than 4 V, and is always lowerthan or equal to 4 V. A differential amplifier may be used in order todetect a minor difference by Equations 1 and 2 due to the difference inCt. FIG. 29 is a circuit diagram showing a differential amplifier thatis used in an embodiment of the present invention. As described above, avariety of amplifiers may be used as the differential amplifier of FIG.29 according to an embodiment of the present invention.

Referring to FIG. 29, the differential amplifier has two inputterminals, in which Vp and Vref are input to each input terminal. Vp isthe potential at the point P in FIG. 11 and Vref is the referencevoltage. The differential amplifier can set an amplification gain(hereinafter, called a gain) by using resistors and capacitors, and theoutput voltage of the differential amplifier is determined according tothe Equation shown on the right side in FIG. 29. The differentialamplifier of FIG. 29 does not indicate only one device, but functionallyindicates the differential amplifier. Therefore, as shown in FIG. 29, aplurality of amplifiers may be used in the inside of the differentialamplifier, and these amplifiers are connected in series to one anotheror connected in parallel with each other. In addition, Vp and Vref maybe connected to the input of another amplifier contained in thedifferential amplifier of FIG. 29.

In addition, although it is not shown in FIG. 29, another signal oranother reference voltage Vref may be applied to the differentialamplifier. In addition, the gain may be also set in a single amplifier,or a plurality of amplifiers. For example, in the case that the gain is12, the gain of a signal is set to 12 when the signal passes through theamplifier whose gain is 12. When a signal having passed through theamplifier whose gain is 4 passes through the amplifier whose gain is 3,it is possible to form the gain of 12. In addition, when a signal passesthrough the amplifier whose gain is 2 two times and then passes throughthe amplifier whose gain is 3 once more, a total gain becomes 12.

According to an embodiment of the present invention, it is preferablethat the gain of the differential amplifier have a variety of multiplesof gains. This is because, since the magnitude of the voltage detectedby Equation 1 or 2 varies depending on the area of the touch pad 10 andthe structure of the touch screen panel 50, the detected voltage shouldbe amplified as large as possible if the magnitude of the detectedvoltage is too small, and the detected voltage should be amplified assmall as possible if the magnitude of the detected voltage is too large.Thus, it is preferable that the TDI 30 have a unit for setting the gain.A gain setting may be set in the register or memory unit 28, and thegain setting may be changed by changing the circuit with reference tothe set value or carrying out a control for changing the circuit.

In FIG. 29, Vp is connected to the differential amplifier through thebuffer 14-1 or directly coupled to the differential amplifier.

Vref is generated in the power supply 47. In FIG. 29, in the case ofVout that outputs the positive (or plus) polarity, if polarities of Vpand Vref that are connected to the input of the differential amplifierare reversed, in contrast to the polarities of Vp and Vref that areconnected to the input of the differential amplifier, the negative (orminus) voltage is output as the output of the differential amplifier. Inthe case that the TDI uses only a positive voltage, the negative outputis not generated as Vout when the output of the differential amplifieris the negative (or minus) voltage, to thus cause a detection error.Therefore, it is necessary to take necessary steps of preventingdetection errors, which will be described later.

Referring to the Equation of FIG. 29 and Equations 1 and 2, in the casethat Vdrv varies from low to high and is applied to Cdrv, the magnitudeof the voltage detected by Equation 1 is equal to or greater than thevoltage detected by Equation 2. In one embodiment, assuming that theresulting value of Equation 1 is 4 V, and the resulting value ofEquation 2 is 3.8 V, the difference between the resulting values ofEquations 1 and 2 is 0.2 V. Therefore, if Vref is set to 4 V, and thegain is set to 10, Vout of FIG. 29 is 0 V such that Vout={10*(4−4)}=0,when Vp follows Equation 1 (i.e., when the touch does not occur), whileVout of FIG. 29 is 2 V such that Vout={10*(4−3.8)}=2, when Vp followsEquation 2 (i.e., when the touch occurs). Thus, it is possible toextract only the difference between Equations 1 and 2 in thedifferential amplifier according to the size of Vref. Here, thereference voltage (Vref) is set to the same value as 4 V that is theresult of Equation 1, or is set to be larger or smaller by apredetermined amount based on the results of Equation 1. For example,Vref is preferably larger or smaller by 1 V or so than the resultingvalue of Equation 1.

On the other hand, the device used in the differential amplifier of FIG.29 is mostly an OPAMP. Thus, in the case that single power having apositive polarity is used in the OPAMP, 0 V (zero volt) is used as theground potential. Assuming that Vout is 0V in this environment, avoltage higher than 0 V is output when 0 V should be output to thuscause a signal detection error, in the case that the OPAMP is not arail-to-rail type. In order to solve this problem, it is desirable thatthe ground potential used in the OPAMP is a potential higher than 0 V.

In one embodiment of the ground potential, the voltage that is ½ of thebias power of the OPAMP is preferably formed as the ground potential.For example, a 5 V power supply is used as the bias power of the OPAMP,the ground potential of the OPAMP will be 2.5 V. In this environment, ameaning that Vout becomes the ground potential is a meaning that theoutput of Vout is 2.5 V. Since the output of Vout is higher than 0 V, asignal is properly output even if the ground potential is output.

It is preferable that Vref should be equal to or larger than thedetection value by Equation 1 depicting the detection voltage when thetouch does not occur. This is because distortion of a signal occurssince, when Vref is smaller than Vp, a negative voltage should be outputas Vout, and when the TDI 30 uses only positive power, a negativevoltage is not output as Vout, referring to the equation on the rightside of FIG. 29. Vref should be at least equal to or greater than thevoltage detected by Vp when the touch does not occur, and the size ofVref varies depending on the size of the touch pad 10 or the structureof the touch screen panel 50. Thus, it is preferable to set the size ofVref by the program or registers by using the DAC, rather than using aplurality of fixed voltages. However, if the DAC may not be used, aplurality of reference voltages are generated to then be connected tothe differential amplifier.

Another reason why the DAC that can produce precisely various sizes ofthe voltages, or a plurality of reference voltages are used in thedifferential amplifier is as follows. Referring to FIG. 25, the othersensor signal wires 22 or the touch pads 10 are present at the right andleft sides of a sensor signal wire 22. With this structure, capacitanceis formed by the equation of FIG. 7 between the sensor signal wires 22or between the sensor signal wires 22 and the touch pads 10. Accordingto the equation of FIG. 7, the longer the distance between twoelectrodes that mutually oppose may be, the higher the capacitance maybe. In addition, in the case that the sensor signal wires 22 and thetouch pads 10 are mutually adjacent to each other, the more the sensorsignal wires 22 adjacent to the touch pad 10, the larger thecapacitance. In addition, capacitance will be generated even at portionswhere the sensor signal wires 22 are connected with the TDI 30, whichwill be variable depending on the materials used in the connection, theprocess conditions, and the connection area. Further, the sensor signalwires 22 in the inside of the TDI 30 may cause capacitances due to theinterference with the signal wires that are disposed in the vertical andhorizontal directions during a layout processing. All of thesecapacitances are parasitic capacitors that are inevitably formed duringa manufacturing process of the touch screen panel 50 or the TDI 30, andare depicted as Cp in Equation 1 or 2.

These parasitic capacitors Cp vary depending on the sensor signal wires22 or the process conditions, or the layout in the inside of the TDI 30.As a result, it may be modeled that different sizes of parasiticcapacitors exist in the respective touch pads 10 of FIG. 25. Accordingto this modeling, the detection voltage described by Equation 1 or 2 orEquation 7 or 8 is different for each touch pad 10, and Vout output bythe calculation equation of FIG. 29 is different for each touch pad 10.

As described above, a meaning of detecting the touch signal is a meaningof obtaining a difference between voltages defined by Equations 1 and 2.As a distribution region where a difference between voltages defined byEquations 1 and 2 exists is wider, the amplifier gain is degraded. Forexample, assuming that a difference between voltages defined byEquations 1 and 2 is 0.2 V in an ideal condition, and can be amplifiedup to 2 V by combination of the ADC, the gain can be set to 10 times.However, assuming that a difference between voltages defined byEquations 1 and 2 is present in the distribution region ranging from 0.1V to 0.4 V, the gain should have 5 since the gain should be inevitablyset on the basis of 0.4 V. As a result, in the case of the touch pad 10having the signal difference of 0.1 V, the amplified value is nothingbut 0.5 V and thus sensitivity is poor. Therefore, in order to increasean amplification ratio, a method of adjusting Vref and thus setting thedistribution area of Vout narrowly is used. One of easy ways toaccomplish this is to adjust Vref of FIG. 29 and make the output voltageof Vout become the ground potential, when the touch does not occur. WhenVout is investigated at the state where the touch does not occur, thevoltage of Vref should be lowered in the case that Vout is higher thanthe ground voltage, while the voltage of Vref should be heightened inthe case that Vout is lower than the ground voltage. This process iscalled a correction or calibration.

FIG. 30 is a circuit diagram showing an ADC converter is connected tothe output end of the amplifier according to an embodiment of thepresent invention. A calibration process will be described as follows,with reference to FIG. 30.

First, at the state where no touch occurs, calibration is to be carriedout. Conditions under which no touch occurs in the touch screen panel 50manufactured by the present invention or a product in which the touchscreen panel 50 is applied, are guaranteed by a manufacturing orshipping process under the control of a producer. Thus, a calibrationprocess that is performed at a state where a product is not under thecondition of use by a user is called a “correction at the factory,”“factory calibration,” or “fac.cal” in abbreviation. The fac.cal processmay be defined as a process of finding a DAC value that is the referencevoltage so that the value output from the amplifier of FIG. 30 becomes acertain value by considering a unique Cp of each touch pad 10 in anon-touch state. Cp has a different capacitance for every detected touchpad 10, and thus the DAC value also will vary for each detected touchpad 10. As described above, the calibration is completed for eachdetected touch pad to have a different DAC value, and an input identicalto the different DAC value should be input to the amplifiercorresponding to each detected touch pad 10 at a step of detecting thetouch signal. The different DAC values should be stored in thenon-volatile memory in the memory unit 28, that is, a flash memory andE2PROM, and is called each time the stored DAC values are used. An“expected value” or “target value” in the calibration process, is avalue (or “ADC output”) output from the ADC converter of FIG. 30, afterhaving completed the calibration. For example, when the expected valueis the ground potential of 0 V, the output of the ADC will be zero inthe ideal case. Otherwise, in the case that the ADC having a 10-bitresolution is used, and the maximum output voltage of the amplifier 14-2is pre-defined as 5 V, if an output voltage of the amplifier 14-2 is 2.5V, the output of the ADC converter 14-3 will be 512 code. Under theseassumptions, the output value of the ADC converter such as 50 code maybe an excellent target value.

It is undesirable that the target value output from the ADC converter is0 code. This is because it is difficult to discern whether the output of0 code is the real 0 code, or whether 0 code is output even with thevalue less than 0 code, since any value should be applied to the DAC ofFIG. 30 in order to begin calibration in the first place, but the outputof the ADC is 0 code even at the conditions where the DAC is appliedlower than Vp and thus the output of the amplifier is negative.Therefore, the target value that should be output from the ADC convertershould be set to be slightly higher than 0 code. For example, the targetvalue is the ADC code that should be a value equal to or greater than 0and 50, 100, or 200 code becomes a good target value. However, if thetarget value is set too high, the fluctuation of the ADC code narrowswhen the touch occurs, and thus the lower target value, the better.

The approximation of the DAC when calibration is completed cannot but beused as the DAC value applied to the amplifier at the time of the firstfac.cal process. This approximation of the DAC may be obtained bycalculation. Referring to the equation of FIG. 29, in the case that Vpis greater than the DAC value, the output of the amplifier 14-2 shouldbe a negative value. The ADC code corresponding to such a negative valueshould be also output as a negative value, but in the case that ADC doesnot output a negative value, the lowest value, 0 (zero) is output. Inthis case, a unit for confirming whether a 0 (zero) value is asubstantially 0 (zero) value, or a value less than 0 (zero) exists isneeded. One of these measures is a unit that is called “Under Flag.”

The “Under Flag” is a signal that is generated when the ADC output valueis 0 (zero). The “Under Flag” is generated in the touch detector 14, thesignal processor 35, or the CPU 40. If the “Under Flag” (hereinafter,abbreviated as UDF) occurs, the signal processor 35 or the CPU 40extracts a voltage higher than the currently applied DAC voltage among aplurality of voltages of the DAC included in the touch detector 14, tothereby connect the amplifier 14-2. However, in the case that UDFcontinues to be generated, UDF does not occur at a certain point and atarget value is output, if a DAC value of a higher voltage.

The fac.cal process to meet the target value will be described asfollows. Assuming that the target value is ADC code of 100, the firstapplied voltage output from the DAC is an estimated value in which 100may be output as the ADC code, which is applied to the amplifier 14-2.If the DAC output having the initially applied voltage value isDAC(init), the ADC output by DAC(init) is higher or lower than 100 codethat is the target value. Otherwise, UDF may occur. If code that isoutput from ADC is higher than 100 code, the DAC output of the voltagelower than DAC(init) should be applied to the amplifier. If code that isoutput from ADC is lower than 100 code, the DAC output of the voltagehigher than DAC(init) should be applied to the amplifier. Finding newDAC is carried out through a trial and error process, but this mayrequire a lot of time. Thus, applying DAC values derived by calculationone-time can preferably shorten a calibration time.

Referring to FIGS. 29 and 30, ADC9(init) that is the output value of theADC that has been output by the first DAC(init) and has not beencalibrated yet is defined as Equation 10, and ADC(target) that is thetarget value by DAC(cal) that is the calibrated DAC value is defined asEquation 11.ADC(init)=Gain(DAC(init)−Vp))  Equation 10ADC(target)=Gain(DAC(cal)−Vp))  Equation 11

By the relationship of Equations 10 and 11, DAC(cal) has the followingrelationship:

$\frac{{{ADC}({target})} - {{ADC}({init})}}{G} = {{{DAC}\left( {{ca}\; l} \right)} - {{{DAC}({init})}.}}$

Accordingly, the DAC(cal) value for output of the target value is avalue that can be calculated by a simple calculation. Thus, instead offinding the target value by a trial and error process, the signalprocessor 35 or the CPU 40 calculates the DAC value for output of thetarget value through an operation, and applies the calculated result tothe amplifier 14-2, to thereby enable to calibrate touch pad 10 within ashort time. On the other hand, assuming that a 10-bit DAC is used andthe output voltage ranges from 0 V to 5 V, 0 V is output from the DAC inthe case that 0 (zero) code is applied to the DAC; 2.5 V is output fromthe DAC in the case that 512 code is applied to the DAC; and 5 V isoutput from the DAC in the case that 1023 code is applied to the DAC.Since the input-output relations of the DAC or ADC can be easily seen byone of ordinary skill in the art, the detailed description thereof willnot be given through the detailed signal flow associated with theinput-output relations of the DAC or ADC, but will be given by referringto only the output value of the DAC or ADC.

FIG. 31 is a flow chart for implementation of a fac.cal process.Referring to FIG. 31, at the first stage (F30 a) of fac.cal, theDAC(init) value is applied to the amplifier. For the operation ofDAC(cal) at the stage (F30 d), the target value is called from thememory (F30 b) and the ADC(init) value is secured (F30 c). The DAC(cal)value secured through the operation is stored in non-volatile memorycontained in the memory unit 28 (F30 e), in which the voltage that isthe output value of the DAC(cal) or the input code of the DAC(cal) togenerate the DAC(cal) is stored as the stored value. Then, when thetouch pads 10 of the touch screen panel 50 of FIG. 25 are scanned on aone by one basis or on a plurality of numbers basis, to thus detect atouch, the voltage that is a unique DAC(cal) value corresponding to anarbitrary touch pad 10 is applied to the amplifier 14-2, together withVp generated by the arbitrary touch pad 10.

It is desirable that the process of performing fac.cal also follows ascan method for the touch detection of the touch pad 10 formed on thetouch screen panel 50 of FIG. 25. That is, if a single touch pad 10 isindividually scanned by using the scan method for the touch detection ofthe touch pad 10, fac.cal is performed on a touch pad 10 at a time,while fac.cal is performed on a plurality of touch pads 10 at a time,for the touch detection of a plurality of the touch pads 10 at a time.This is because the circuit design is complicated, the volume of the TDI30 is increased, to thereby raise the cost, and the operations of theCPU 40 or signal processor 35 for processing the signals are increasedand complicated, since the multiplexer (MUX) used for the touchdetection process may not be used but the multiplexer (MUX) with adifferent sized input and output should be used if the method ofscanning the touch pads 10 is changed in the calibration process.

The touch detection device according to one embodiment of the presentinvention decreases the variation in the detected voltage of the touchthat is caused by the position of the touch pad 10 and thecharacteristic of the parasitic capacitance through fac.cal using theabove-mentioned DAC, to thereby provide an accurate touch detection.

After the completion of fac.cal, a product in which the touch screenpanel 50 according to the present invention is applied is sold to a userand exposed to a variety of use environments. For example, a change intemperature may also occur and even the time elapses. Due to theseenvironmental changes, characteristics of the touch pads 10 and the TDI30 formed on the touch screen panel 50 may also vary. For example, theresistance of the sensor signal wires 22 may be changed and the Cp valuemay be changed, due to the temperature change. In addition, as the timeelapses, the protective layer 24 to protect the touch pad 10 is wornout, and then change of d occurs in Equation 3. As a result, the changeof sensitivity may also occur. Extracting the touch coordinate or thetouch area by considering these changes in real time, is called areal-time calibration (hereinafter, abbreviated as RTC).

In order to calculate the touch area or the touch coordinate, a numberof values are stored in the memory unit 28. For example, in order tocalculate the touch area or touch coordinate of a certain touch pad, thevoltage detected in the touch pad depending on Equation 1, that is, thevoltage at the time of a non-touch operation is converted into a digitalvalue in the ADC converter 14-3 to then be stored in the memory unit.Vpre that is the charging voltage is also stored in the memory unit, andvalues of Vdrv and Cdrv are also stored in the memory. This is becauseVpre, Vdrv or Cdrv can be applied in different size for each touch pad.If Cp is too large and thus the touch sensitivity falls in a certaintouch pad 10, Vdrv or Cdrv is made to become large, according toEquation 1 or 2, to thereby increase the voltage detected due to the D/Band to thus improve the sensitivity.

If these values written in the memory unit are used in real time withoutany calibration, errors can occur at the time of the touch detection.For example, the voltage detected at the time of the non-touch operationis a voltage that is actually detected theoretically in accordance withEquation 1. The analog voltage output from the amplifier 14-2 isconverted into a digital value in the ADC converter 14-3. A differencebetween the digital value and the ADC value detected in accordance withEquation 2 at the time of a touch operation, is detected, to thusextract the touch area and the touch coordinate. Here, when the voltagedetected in accordance with Equation 1 at the time of the non-touchoperation has been stored in the memory unit, and a difference betweenthe stored value and the value detected in real time in accordance withEquation 2 at the time of a touch operation is detected, the signaldetected in real time reflects all changes depending upon anenvironment, but the value stored in the memory unit is a value storedthrough the fac.cal process at the time of shipment from a factory,which does not reflect the changed characteristics due to theenvironmental factors to thereby cause the detection error. Accordingly,values that are stored in the memory unit should also reflect thechanged characteristics through RTC to then be re-stored.

For this purpose, the memory areas of the memory unit storing thecalibrated values 28 is preferably separated into two. In the case thata different type of correction is required other than fac.cal or RTC,the memory areas should be separated into more areas.

First, when considering only fac.cal and RTC, the values detected orcalculated through the fac.cal process are stored in one of two separatememory areas, and the values detected or calculated through the RTCprocess are stored in the other of two separate memory areas. It may benecessary to determine whether to use the fac.cal data or the RTC datain the touch detection process. This is because to use the RTC data inorder to reduce the detection errors may cause more serious detectionerrors than to use the data obtained through the fac.cal process, sincedata stored in the memory unit through the RTC has a high probability ofnoise affected values under a noisy environment. In the case that theCPU 40 or the signal processor 35 has a unit capable of detecting thesize of such noise, it is possible to determine whether to use thefac.cal data or the RTC data depending on the size of the noise.

The CPU 40 or the signal processor 35 may detect the size of the noise tusing the value of the ADC converter 14-3. In the case of sequentiallyscanning the single touch pad 10 or the touch pads 10 included in thelongitudinal or transverse group, and detecting the touch signal, thevoltage is not usually detected by the D/B only one-time, but thevoltage is detected a plurality of times and filtered, to thus extractdesired data. This technique is intended to remove noise that isincluded in the detected voltage and extract a more stable signal. Ifany of the touch pads 10 is scanned about 100 times, and the detectedvalue is stored in the memory each time at every scan, the signal bandof the detected signal 100 times will be formed. For example, the signalband may be formed of 2 V to 4 V, or may be formed of 1 V to 5 V. In thecase of the two signal bands, the central value is identically 3 V, butthe first signal band is 2 V (i.e., 4 V−2 V), and the second signal bandis 4V (i.e., 5 V−1 V). Therefore, it can be expected that the touchsignal to generate the signal band of 4 V, generates noise greater thanthe touch signal to generate the signal band of 2 V. By using thistechnique, since the TDI 30 can determine the size of noise by using theoutput of the ADC converter 14-3, the TDI 30 may determine whether touse the fac.cal data or the RTC data stored in the memory unit dependingon the size of the noise. According to one embodiment of the presentinvention, data to the memory unit may be differently taken depending onthe size of the noise. The TDI 30 may determine which data can be usedat a given number of conditions. Such a determination may be conductedby a program in the TDI 30, or may be carried out by the register.

The RTC is preferably performed at a non-touch state. For example, whena user performs a call or other operations by using a mobile phone inwhich the touch screen panel 50 of the present invention, the RTC is tobe carried out at a non-touch state after the call or other operationshave been completed. According to the basic idea of the calibration, theDAC value is found when no touch occurs, in which the ADC value is thetarget value, and the found value is stored in the memory unit, and theDAC value is called and used, when the touch signal of the correspondingtouch pad 10 is detected. Therefore, if a calibration is performed whena touch occurs, the touch detection error occurs.

In order to enforce the RTC, it is important to distinguish whether atouch occurs at the point in time when the RTC is in progress. Thus, itis important to first enforce a determination on whether or not a touchoccurs.

Then, the following embodiment determines whether or not a touch occurs.At the first point in time at which the RTC is performed, the fac.caldata should be used. The ADC value detected by using the fac.cal data ispresent between 0 and 1023 code if the ADC has the 10-bit resolution.The CPU 40 or the signal processor 35 calculates the touch area by usingthe ADC value, in which the touch area is also present within a specificrange, like the ADC. Thus, the extracted ADC value or the calculatedtouch area reacts according to the contact area between the touch pad 10and the touch unit such as the finger 25, to thus be linearly ornon-linearly increased or decreased. In this specification, it isassumed that as the contact area becomes large, the extracted ADC valueor the calculated touch area increases linearly. Since the extracted ADCvalue or the calculated touch area is increased linearly between 0 and1023 code in proportion to the touch area, the ADC value when a touchdoes not occur is the above-described “target value” and as the contactarea becomes large since the touch occurs, the ADC value or the toucharea value increases. Under such circumstances, by setting a thresholdvalue, it is possible to judge whether or not the touch occurs. If it isdetermined that a touch has occurred when the ADC value or thecalculated touch area is over 300, the threshold value is determined as300. Therefore, if the ADC value or the calculated touch area isdetected as 300 or higher, it can be determined that the touch hasoccurred. When it is determined whether or not a touch occurs, it ismore convenient to refer to a group of a plurality of the touch pads 10that are distributed over a large area adjacent to each other, ratherthan considering the ADC value or the calculated touch area for one ofthe touch pads 10. If the touch unit such as the finger 25 is in contactwith a plurality of the touch pads 10, the Gaussian curve is formed. TheTDI 30 determines the touch has occurred if a normal Gaussian curve isdetected. If a Gaussian curve is not detected, it can be determined as anon-touch state. Even though the threshold value is equal to or lessthan 300, if a Gaussian curve is detected and it is determined that aweak touch has occurred, the RTC process may not be conducted.

The RTC process proceeds in the same process as that of the fac.calprocess. A DAC(cal) value for outputting a previously entered targetvalue is extracted and the extracted DAC(cal) value is stored in thememory unit. The extracted DAC(cal) value has its own value for eachtouch pad 10. The DAC output value corresponding to the touch pad 10 isconnected to the amplifier when the touch detection sequence of thecorresponding touch pad 10 has come.

The TDI 30 has a unit for determining whether a touch will be detectedby using the fac.cal data and whether the touch will be detected byusing the RTC data. Such a unit may be usually set as a register, or maybe located on the memory unit and the program. If the unit is set as theregister, the corresponding bit is set to high or low, to thus take theRTC or fac.cal data. The corresponding bit may be automatically changed,or may be changed by the user, by determining change of thecorresponding bit in the TDI 30.

As described above, when a touch has occurred, the RTC process shouldnot be performed, but the region of the detected ADC value or thecalculated touch area value may be referred to for determining whetherthe RTC process proceeds.

FIG. 32 is a diagram illustrating an example of setting regions for realtime calibration (RTC) according to an exemplary embodiment of thepresent invention. Referring to FIG. 32, the peak of a square wave ofFIG. 32 is a voltage by the D/B which is detected by Equation 1. Thislevel is a level at the time of no touch, that is, when no touch hasoccurred. If the voltage at an instant time when Vdrv is changed fromlow to high when the touch has occurred is applied to Cdrv, thedetection voltage due to the touch defined as Equation 2 is formed so asto be lower than the voltage by Equation 1. Accordingly, the detectionvoltage due to the touch defined as Equation 2 is formed lower than thevoltage of the peak of FIG. 32. In the foregoing description, it hasbeen described that it is determined whether a touch has occurred by athreshold value, and the threshold value is set at the boundary betweenthe area 2 and area 3.

Meanwhile, the area 1 and the area 2 are set around the level at thetime of no touch. If the Cp value is reduced, according to theenvironment and the lapse of time, the “level at the time of no touch”will be adjusted upward. Thus, according to the changes of the size ofthe values included in the denominator and the numerator of Equation 1or 2, the “level at the time of no touch” will be changed upward ordownward.

The “level at the time of no touch” of FIG. 32 is a value set by theresult of the fac.cal process, and may be a value that is changedaccording to the lapse of time. Accordingly, the area 1 and the area 2that are changed upward or downward based on the “level at the time ofno touch” can be considered as a value that is formed when the targetvalue has changed due to the fac.cal process before the RTC process.

Here, the area 1 of FIG. 32 is an area where it is unnecessary toperform the RTC. Typically, there is an item to inspect a touchsensitivity in a manufacturing specification or a shipment performancereport for the touch screen panel 50 of the present invention. The touchsensitivity is specified together with tolerance. Thus, the area 1 is inthe range of an area where the touch sensitivity is not affectedalthough the fac.cal result value is changed by a predetermined value tothus cause an error.

However, the area 2 is in the range of an area where the touchsensitivity is affected, and the RTC process should be conducted in area2. As explained earlier, the ADC value or the calculated touch areavalue changes linearly or non-linearly according to the size of thetouch, and thus it is possible to distinguish the area 1 and the area 2by the operation. The area 2 is an area in which an error occurs upondetection of a touch area if no calibration is performed, and an errorrange is a region beyond the range of the shipment performance report.

On the following, a signal processing operation of a touch detectionmethod using the D/B phenomenon according to the present invention willbe described.

FIG. 33 shows a conventional touch detection circuit.

Since the touch detection signals occurring in the touch detectors inthe capacitive TDIs 30 according to the prior art are weak, the touchdetection signals are integrated several times and the integrated touchdetection signals are amplified again, to then be used for touchdetection. FIG. 33 shows an example of a conventional capacitive touchdetection circuit, which illustrates “Basic Circuit Model” of QT60xx5Bseries shown in FIGS. 1 to 5 of Application Note R1.06 regardingQT60xx5B of “QUANTUM” company. Referring to the waveform diagram onbottom right of the right side of FIG. 33, the voltage level of “AmpOut” is elevated in synchronism with the switching of “Xn.” That is,whenever the switching of Xn is performed, charges are accumulated in Csor Ca connected to a “Charge Integrator,” and as the amount ofaccumulation increases, the voltage of Ca or Cs gradually increases inproportion to the charge amount Q by the classical equation formedbetween the voltage and charge amount Q. Since the voltage level of thevoltage due to the charges accumulated is still low, the voltage isamplified in the amplifier “Amp” and the amplified result is output.These signals are shown on bottom right of the right side of FIG. 33. Insuch a conventional touch signal detection method, since an “X drive”that generates a driving signal should perform a high speed switching aplurality of times in order to detect a touch signal, and a number oftimes of the switching should increase in order to increase a detectionaccuracy, the resistance of the sensor signal wires 22 connected to an“X electrode” that is a touch pad in the X-axis direction and a “Yelectrode” that is a touch pad in the Y-axis direction should be low.This is because a signal delay occurs due to the action of a resistorconnected with the sensor signal wires if the resistance of the sensorsignal wires 22 is increased, and thus it is not possible to detect asignal at high speed.

According to the conventional method, the resistance value is limited toan extent of about 20 Kohm. In order to apply the low resistance to thesensor signal wires 22, the sensor signal wires 22 made of a transparentconductive material such as ITO or CNT according to an embodiment of thepresent invention are not allowed to be used, but the metal-based sensorsignal wires 22 made of copper (Cu) or silver (Ag) should be used. Themetal-based sensor signal wires 22 made of copper (Cu) or silver (Ag) isnon-transmissive and visible. Accordingly, when wirings are made on anactive area (A/A) in a display device shown in FIG. 25 according to theembodiment of the present invention, wirings are not performed becauseof a problem that wirings stick out, and wirings should be wired onnon-visible areas (or back matrix; BM) that are the left and right areasof the A/A. This causes the bezel of a product where the touch screenpanel 50 is applied to widen, thus causing a problem that the value ofthe product drops. Another problem with the conventional product, inorder to secure the signal, the driving device (that is the “X” drive)should perform the high speed switching, to thereby cause the EMSproblem more likely.

Further, as can be seen from the equation formed between the voltage andcharge amount, the voltage detected in the conventional case of FIG. 33is sensitive to the variation of Cs or Ca that is the value of thecapacitance of the capacitor C. Therefore, in order to compensate forthese issues, that is a problem that calibration should be oftenperformed.

However, referring to FIG. 11 according to the embodiment of the presentinvention, a signal is detected by performing a switching on asingle-time basis according to the present invention, while a signal isdetected by performing a switching on a plurality of times basisaccording to the conventional case. This is because the charge signalshould be applied to the touch screen panel 50 according to the presentinvention each time it is detected whether or not a touch occurs, andaccordingly the initial voltage (the charging voltage before the drivingvoltage is applied) at the point P in FIG. 11 becomes always thepotential level of the charging voltage, to thus make it impossible todetect the signal a plurality of times. Further, since the size of thedetection voltage can be adjusted in size by using the size of Vdrv orCdrv, or Vh or Vl as in Equation 1 or 2, it is possible to artificiallyincrease the detection voltage by adjusting the size of Vdrv or Cdrv, orVh or Vl if the size of the detection voltage is low.

Accordingly, in order to detect a touch signal of the touch screen panel50, the switching speed of applying Vdrv may be slow, and thus theresistance value the sensor signal wires 22 connected to the touch pad10 may be high.

If a signal is detected by performing the switching 100 times accordingto the conventional method, the resistance value of the sensor signalwires 22 may be high 100 times, under the assumption that the sensorsignal wires 22 according to the present invention achieve the sametouch detection rate as the conventional art case. Also, since the touchis detected by only one-time switching, there are advantages that EMSproblems are significantly lowered compared to the conventional art.Also, referring to Equation 1 or 2, capacitors are present in thenumerator and denominator thereof, and in the case that a value of Cdrvis significantly larger than the other capacitors, the potential of thepoint P has no major changes although Cdrv or the values of thecapacitors connected to Cdrv may cause a change.

According to another advantage of the present invention, a number ofcapacitors connected to the point P in FIG. 11 act as the memory unit.For example, since the detected voltage is stored in Cdrv, Cvcom, or Cpeven if the sensor signal wires 22 are open after the voltage detectiondue to the D/B has been completed, the touch signal operation is notprevented. Although it will be described later, it is possible to detecta touch signal that is not affected by noise by using such a function.

According to an embodiment of the above-described present invention, itis possible to detect whether or not a touch occurs at a substantiallysingle time, and the drive at a high frequency is unnecessary, the touchdetection is strong against noise, and it is possible to performaccurate touch detection even with a high resistance.

FIG. 34 illustrates a configuration of a thin film transistor (TFT)substrate for a liquid crystal display (LCD), and particularly, showsthe configuration of the TFT substrate of an IPs (In Plane SwitchingMode) that is a transverse electric field mode. In contrast to theaforementioned embodiment, the common electrode 220 is not formed in thecolor filter 215 in the LCD of the transverse electric field mode, butis formed only in a part of an area of the TFT substrate 205. Referringto FIG. 34, the LCD of the transverse electric field mode will bedescribed below briefly.

As illustrated in FIG. 34, gate lines 242 and data lines 244 arearranged in the length and breadth on the TFT substrate 205, and areasthat are sectionalized by the gate lines 242 and the data lines 244 formpixels. A TFT 250 for switching an image signal is mounted in a pixel. Agate electrode 251 of the TFT 250 is connected to a gate line 242 toreceive a scanning signal, and a source electrode 253 and a drainelectrode 255 thereof are connected to a data line 244 and a pixelelectrode line 248, respectively. In addition, a semiconductor layer 257of the TFT 250 forms a channel between the source electrode 253 and thedrain electrode 255 in order to apply an image signal to a liquidcrystal layer. As shown, a common electrode line 246 is formed in thepixel in parallel to the pixel electrode line 248.

In the LCD having such a configuration, in the case that the TFT 250 isactivated, and thus an image signal is applied to the pixel electrodeline 248, a substantially parallel transverse electric field occursbetween the common electrode line 246 and the pixel electrode line 248,and the liquid crystal molecules move on a plane. However, as shown, thecommon electrode line 246 is formed in only a partial area. Thus, in thecase that the touch screen panel 50 shown in FIG. 25, is located on theupper surface of the touch pad 10 of the LCD in the transverse electricfield mode, or the touch pad 10 is patterned on the upper surface of thecolor filter 215 of the LCD, the capacitance Cvcom that is formedbetween the touch pad 10 and the common electrode line 246, is formedsmaller than the case that the common electrode line 246 is formed onthe entire area of the TFT substrate 205.

Since the LCD that is made in the transverse electric field mode has nocommon electrode formed on the entire area of the color filter of 215,the LCD is vulnerable to an externally applied ESD. Thus, as shown inFIG. 35, a transparent conductive material such as ITO, ATO or CNT iscoated on the upper surface of the color filter 215 in a full areapainting manner, to then be connected with a predetermined DC potential,normally connected with the ground potential of 0 V. In the LCD made inthe transverse electric field mode, a layer that is coated on the uppersurface of the color filter 215 and connected with the ground potentialis named a “back ground.”

Referring to FIGS. 36 and 37, a touch detection method according to anembodiment of the present invention that may be used in the transverseelectric field mode will be described as follows.

FIG. 36 is a cross-sectional view illustrating a backgroundconfiguration on a transverse electric field mode liquid crystal display(LCD) substrate according to an exemplary embodiment of the presentinvention, and FIG. 37 is a front view of a configuration in which atouch detection device is applied to a transverse electric field modeLCD substrate according to an exemplary embodiment of the presentinvention. FIGS. 36 and 37 illustrate a case that touch pads 10 of thepresent invention are patterned in a color filter 215 of the LCD(hereinafter, called an on-cell-touch), according to an exemplaryembodiment of the present invention. The touch pads 10 may be mounted inthe inside or outside of the A/A 90 of the LCD. A non-visible area 92 onwhich images are not displayed is located on the edge portion of the LCDsubstrate 200, but the touch pads 10 according to the present inventioncan be also mounted. Also, the touch pads 10 are connected to the TDI 30by using a flexible circuit board 96 such as FPC or COF.

In this configuration, except for the touch pads 10 that are being usedin the process of the touch signal detection, the other touch pads 10should be connected to the ground. Here, the ground is a DC voltage with0 V or a predetermined potential.

FIG. 38 is a circuit diagram illustrating a configuration in which touchpads 10 are used as a background according to an exemplary embodiment ofthe present invention. Referring to FIG. 38, a touch detection circuitis configured to have touch pads 10 connected to respective switchingunits 16. Accordingly, the touch pad 10 will have three types of states.The first state of the touch pad 10 is a floating state where the touchpad 10 is not connected to the switching unit, the second state of thetouch pad 10 is a state where the touch pad 10 is connected to theswitching unit, and is connected to the ground potential that is one endof the switching unit, and the third state of the touch pad 10 is a casewhere the touch pad 10 is connected to the touch detector 14 that isconnected to one end of the switching unit.

In this configuration, referring to FIGS. 36 and 37, except for thetouch pads 10 a that are being used for the touch detection, the othertouch pads 10 b that are not used for the touch detection should be allconnected to the ground. Thus, since all the touch pads 10 except thetouch pads that are being used in the progress of the touch detectionare connected to the ground potential, the touch pads 10 act as abackground.

Further, since the charging voltage due to Vpre is applied to the touchpads 10 that are being used for detecting a touch, for a certain amountof time, a discharge path is formed by the charging unit 12, and thusnoise such as the ESD may be discharged to the outside of the touchscreen panel 50. Accordingly, it is possible to act as a background.Thus, referring back to FIG. 38, the touch pad 10 a that is being usedfor detecting a touch, or the touch pads 10 b that are not being usedfor detecting the touch can play a role of the background.

In the embodiment of FIG. 37, a case in which a touch pad 10 that isdetecting a touch is one has been also exemplified, but a group of allthe horizontal touch pads 10 of FIG. 37 or a group of all the verticaltouch pads 10 of FIG. 37 may detect a touch simultaneously.Alternatively, a group of a plurality of touch pads 10 may detect atouch in a specific area. Otherwise, a group of a plurality of touchpads 10 may detect a touch randomly. Even in this case, the remainingtouch pads 10 except for the touch pads 10 that are being used fordetection of a touch should be connected to the ground by the switchingunit.

In the embodiment of FIG. 38, if the signal detection operation of thetouch pad 10 a that are being used for detecting a touch signal iscompleted, the completed touch pad 10 a is connected to the ground byoperation of the switching unit. Thereafter, one of the touch pads 10 bis disconnected from the ground and is newly connected to the touchsignal detector 14, according to a predetermined sequence. If aplurality of detection circuits are used as shown in FIG. 38, thelongitudinal touch pads 10 and the transverse touch pads 10 aresequentially scanned in the case that the touch pads 10 are formed inthe longitudinal and transverse directions as shown in FIG. 37, tothereby detect and complete a touch. Thereafter, since the touch pad maybe connected to the ground, it is possible to detect a touch signalearlier than the case of scanning the individual touch pad 10.

Referring back to FIG. 37, since the upper and lower areas of the touchpads 10 are empty, the noise such as ESD is applied to the LCD, and thusthe electric field can be formed in the liquid crystal of the displaydevice located below the empty space. Accordingly, malfunction of animage quality on the display device may occur. Further, even in an areawhere a plurality of sensor signal wires 22 are laid on the left andright sides of the touch pads 10, spaces are present on the left andright of the signal wires. As a result, through these spaces,malfunction of an image quality can occur due to noise such as ESD.

FIG. 39 shows an exemplary embodiment of the present invention in orderto solve the above-described problem, and is a diagram illustrating alayout of sensor signal wires 22 according to the exemplary embodimentof the present invention.

A LCD has dots 275 in which each dot is composed of three pixels Red,Green, and Blue. In the present invention, individual Red, Green or Blueregions are defined as pixels or picture elements. Referring again toFIG. 39, in the case that there are no sensor signal wires 22 betweentouch pads 10 g and 10 h of FIG. 39, the space between the touch pads 10g and 10 h, should be narrower than the pixels. Thus, although noise isapplied to the narrow region between the touch pads 10 g and 10 h, thenoise is discharged by the ground potential connected to the touch pads10 g and 10 h that are located in the top and bottom thereof, to therebyprevent the operation of the pixel from being affected.

Furthermore, the space between the sensor signal wires 22 is narrowerthan the pixels. Referring to the sensor signal wires 22 a and 22 b, thespace between the two sensor signal wires is narrower than the width ofthe pixel. Thus, although noise is applied to the narrow region betweenthe sensor signal wires 22 a and 22 b, the noise is discharged to theoutside through the sensor signal wires 22 a and 22 b placed in the areaof the pixel and connected to the ground, and thus malfunction of theimage quality of the pixel does not occur.

Referring to FIG. 25 or 37, the space between each of the touch pads 10forming the touch detection pattern and each of the sensor signal wire22 occurs, and the farther from the TDI 30 it is, the wider the area ofthe space is. A transparent conductive material such as ITO that is usedto form the touch pads 10 is not coated or printed in the spaces betweenthe touch pads 10 and the sensor signal wire 22, to thus cause the touchpads and the sensor signal wires to be noticeable, and to thereby leadto a poor display quality and cause a poor image quality due to noisesuch as ESD. Therefore, measures of improving visibility and preventingthe image quality from going bad need to be taken for the spaces betweenthe touch pads 10 and the sensor signal wire 22.

FIGS. 40A to 40C show approaches to solve the above problems, in which acharging unit such as a filled Area or additional area is provided in aspace formed between the touch pads 10 and the sensor signal wires 22.Referring to FIGS. 40A to 40C, the space filler unit 11 is filled inthis empty space. The space filler unit 11 is filled with the samematerial as that used in the touch pad 10, and may be formed into acompletely full state without an open space by a filling process, or maybe formed of a mesh structure. In addition, the space filler space 11may be extended from the touch pad 10 as shown in FIG. 40A, may beconnected with the sensor signal wire 22 as shown in FIG. 40B, and mayremain floated as shown in FIG. 40C without connected to the sensorsignal wires 22 or the touch pads 10.

On the other hand, in the FIG. 41 embodiment, it is assumed that a dropof water or sweat or a conductor 26 such as a metal lies between thetouch pad 10 a that is detecting a touch and the touch pad 10 bconnected to the ground potential. Such conductor 26 is not directly incontact with the touch pad 10, but lies on the upper surface of theprotective layer 24 as shown in FIG. 12 or 13. As shown in FIG. 41, thisenables a path of movement of charges to be formed in the touch pad 10 athat is detecting a touch, to thus charge Ct. Referring to FIG. 13 or12, Ct that is formed by the equation of FIG. 7 is formed between thetouch pad 10 and the protective layer 7 and the size of the capacitanceCt is determined according to the contact area between the touch pad 10and the conductor. Since the conductor 26 of FIG. 41 is connected to thetouch pad 10 b connected to the ground in the touch state, a path ofmovement of charges is formed between one side of the touch capacitorCt1 of the touch pad 10 a and the touch pad 10 b connected to theground. Since the touch capacitor Ct2 is also formed in the touch pad 10b connected to the ground, one side of the touch capacitor Ct1 has apath that is connected to the ground through Ct2. Since Ct1 is chargedwhen the touch pad 10 a for detecting a touch is charged through thecharging unit 12, even if the touch is not a touch that occurs due tothe bodily finger 25 by Equation 2, it is recognized as occurrence ofthe touch.

In order to prevent such problems, the touch pad 10 b (hereinafter,called a non sensing pad, and abbreviated as NSP) connected to theground potential without detecting a touch, is disconnected from theconnected ground potential to thus maintain a floating state when thetouch pad 10 a (hereinafter, called a sensing pad, and abbreviated asSP) is detecting a touch under the touch signal detection.

By the above-described configuration of the present invention, the touchpad has three states such as the ground state, the floating state, andthe connected state, to thus support a transverse electric field modeliquid crystal display device, and prevent errors that may occur in thetouch pad where no touch has occurred. In the case that the displaydevice has no transverse electric field mode, the touch pad may notselect the ground state.

Detailed description will follow with reference to FIG. 42. FIG. 42 is awaveform diagram except for a portion being synchronized with a commonvoltage in an embodiment of FIG. 22, which illustrates an opening of theNSP according to an embodiment of the present invention.

An area 1 of FIG. 42 is an interval at which capacitors connected withthe touch detector 14 are charged and a voltage due to the D/Bphenomenon is induced. Referring to FIG. 41, when capacitors connectedwith the touch detector 14 are charged by the charging unit 12, Ct1 andCt2 are also charged by the conductor 26. Accordingly, in order toeliminate the charge path of Ct1, all the NSPs 10 b are floated and thedischarge path is not formed. The CPU 40 or the signal processor 35controls the switching unit 16, to maintain all the NSPs 10 b connectedto the switching unit 16 to be in the floated state. In the FIG. 42waveform diagram, a meaning of the NSP signal in a high state means thatthe NSP is opened or in the floated state, while a meaning of the NSPsignal in a low state means that the NSP is connected to the ground viathe switching unit 16.

It is preferable that the NSP 10 a is opened before the touch capacitorCt1 formed in the touch pad 10 a that is used to detect a touch ischarged. It is preferable that an open time is done from 1 ns to 100 msbefore charging begins.

Thus, referring to FIG. 42, the NSP 10 a has been opened before thecharging unit 12 is turned on by Vg. The NSP can be open even duringcharging. The TDI 30 has a unit for setting a point in time at which theNSP is opened. This is driven by a value that is stored in a register ora memory unit or a program executing the CPU 40. For example, suppose aregister. When selecting the address 00h of the register, the NSP may beopened within 1 ns, while when selecting the address 0Fh of theregister, the NSP may be opened within 100 ms.

The area 1 is an interval at which the charging is completed by thecharging unit 12, and then the voltage is formed due to the D/Bphenomenon, to also complete stabilization. Then, the voltage due to theD/B is detected. The voltage detected in the area 2 is subjected toundergo a sampling process by which the voltage is stored in a storageunit such as a sample & holder and a capacitor (not shown) in the insideof the touch detector 14. An area 3 is an interval at which sampled datais amplified or is converted into a digital value in an ADC converter14-3, after the completion of the sampling process. Therefore, the area3 at which the sampling has been completed is an area where the openedNSP may be connected to the ground. It is desirable that connection ofthe NSP to the ground is made within from 1 ns to 100 ms from a point intime of termination of the area 2 whose sampling has been completed.

On the other hand, the touch pad 10 that is detecting the common voltageshould be also opened and closed (or connected to the ground by theswitching unit) at the same point in time as that of the NSP, to thusblock a path of movement of the charges due to the touch pad 10 that isdetecting the common voltage, and to thereby prevent malfunction of thetouch operation.

The TDI 30 has a unit for determining a point in time at which theopened touch pad 10 is closed. This is driven by a value that is storedin a register or a memory unit or a program executing the CPU 40. Forexample, suppose a register. When selecting the address 00h of theregister, the NSP may be opened within 1 ns, while when selecting theaddress 0Fh of the register, the NSP may be opened within 100 ms.

When the time that is taken until the NSP 10 b is opened is longer, thetime that is taken when the touch pad acts as a background is shortened.As described above, this may cause a poor image quality due to noisesuch as ESD with high probability. Thus, measures to reduce the opentime of the NSP 10 b is needed.

Referring to FIG. 41, Cdrv, Cvcom, and Cp are connected in parallel withthe touch capacitance Ct. In the typical embodiments of the presentinvention, Cvcom or Cdrv has a larger capacity a couple of times thanCt. Thus, the potential at the point P is not greatly affected althoughthe touch capacitor Ct is uninstalled after the completion of the chargesharing at the point P by the D/B. One of these reasons is that thepoint P is floated in the Hi-z state with the exception of beingcharged, and thus there is no discharging path. The fact that theremainder capacitors without Ct will act as a memory unit, and thecharges are preserved, provides a theory in which there is nomalfunction for the touch signal detection even though Ct is removed,since the voltage due to the D/B is generated by using Equation 2 byreflecting the capacitance of Ct at a state where Ct has been connected,and the resulting voltage is stored in a capacitor acting as the memoryunit.

Referring again to FIG. 41, even if the SP 10 a that is the touch pad 10a used for the touch detection is opened, a path of movement of chargesformed by the conductor 26 is blocked. Thus, opening of the SP 10 a isalso one of methods of preventing touch malfunction caused by a drop ofwater, or the conductor 26 such as metal.

FIG. 43 is a waveform diagram showing an open of the SP 10 a accordingto an embodiment of the present invention. In FIG. 43, the flow or timeof all signals except SP 10 a is the same as in FIG. 42.

Referring to FIG. 43, the voltage by the D/B is formed by the drivingvoltage Vdrv and the SP 10 a in the area 1 is opened after the chargesharing has been completed between all the capacitors connected to thepoint P. Here, a meaning of the SP that is in a high state, is that theSP is opened, while a meaning of the SP that is a low state, is that theSP 10 a is connected to the ground. If the SP is opened, the NSP 10 a isagain connected to the ground, which is made within 1 ns to 100 ms afterthe SP has been opened.

A point in time at which the SP 10 a is opened may be synchronized withVg, Vdrv or a common voltage (not shown). After the SP 10 a has beenopened and then the sampling has been completed in the area 2, the SP 10a is preferably connected to the ground in the area 3.

After the sampling has been completed in the area 2, the SP 10 a isconnected to the ground within 1 ns to 100 ms.

If one SP 10 a still acts as the SP 10 a in the following sensingsequence, the SP 10 a should be connected to the point P before thecharging is completed. Referring to FIG. 43, the opening and closingtime of the NSP has an effect of being shortened in conjugation with theSP 10 a at work, which gives a great help when the touch pad 10 acts asa background.

The TDI 30 has a unit for controlling an opening and closing time of theSP 10 a, and is carried out by a register or memory unit, or by aprogram. In addition, the opening of the SP 10 a plays a role ofreducing an inflow time of noise introduced through the SP, and thusalso serves to weaken the noise affecting at the point P.

Referring to FIG. 37, the touch pads 10 of R1 are farther away from theTDI 30 than the touch pads 10 of R7, and thus the resistance formed bythe sensor signal wires 22 that form a sensor pattern is larger in thetouch pads 10 of R1 than the touch pads 10 of R7 and the parasiticcapacitance Cp is also larger in the touch pads 10 of R1 than the touchpads 10 of R7. Therefore, as the SP 10 a shown in FIG. 43 is opened, theopening time of the SP 10 a can be determined considering the resistanceand the capacitance. This is because a change in voltage or the chargesharing due to the D/B in Ct by Vdrv applied to Cdrv is delayed by afactor according to a multiplication of RC (or a coupling of a resistorand a capacitor), since the resistance or parasitic capacitance of thesensor signal wires 22 connected with Ct formed in the touch pad 10becomes large as the touch pad 10 is farther away from the TDI 30.Therefore, if the same opening time of the SP 10 a is applied to all ofthe touch pads 10 a of the touch screen panel 50, the touch pad 10 closeto the TDI 30 has no specific problems since the touch pad 10 close tothe TDI 30 performs the signal sampling after the completion of thecharge sharing, but the touch pad 10 far away from the TDI 30 may lowerthe touch sensitivity and cause a touch coordinate detection error,since the touch pad 10 far away from the TDI 30 performs the signalsampling after the non-completion of the charge sharing between thecapacitors connected to the point P.

In order to solve this problem, measures of varying the opening time ofthe SP 10 a by the position of the touch pad 10 are needed. For example,in FIG. 37, the touch pad 10 of R1 is the farthest from the TDI 30 andthus resistance or the parasitic capacitance is large in size.Accordingly, a unit for adjusting the opening time of the touch pad 10when the touch pad 10 is activated as a SP, is separately provided.Further, units for adjusting the opening times of the touch pads 10 whenthe touch pads 10 of all the rows such as S2 or S3 are activated as SPs,are separately provided by row. Such units are performed by a registeror a memory unit or a program within the TDI and the detailed method isthe same as described above.

According to such an embodiment of the present invention, the time toopen the touch pad is variably performed, depending on the location ofthe touch pad, which is robust to the disturbance or noise and enablesaccurate touch detection.

Meanwhile, the same opening time can be applied in SPs of R1 and R2 andthe same opening time can be applied in SPs of R1, R2 and R3. The numberof the touch pads 10 included in a group of opening the SP at the sametime can be selected by a designer. Here, the number of the touch pads10 included in the same group should be adjusted depending on the sizeof the resistance and the parasitic capacitors.

The TDI 30 has a unit for selecting the number of the touch pads 10included in the group of performing an SP open operation at the sametime. Referring to a case where a register is used for this purposeaccording to an embodiment of the present invention, if an address 00 ofthe register is selected, all of rows have the individual SP open time,and if an address 01 of the register is selected, two rows are includedin the same group. According to one embodiment, two rows such as R1 andR2 or R3 and R4 are included in the same group. Otherwise, if an address03 of the register is selected, five rows are assigned in the samegroup, to activate the rows of R1 to R5 at the same SP open time.

The resistance values of the touch pads 10 to be included in a groupthat performs the SP open operation at the same time are preferably thesame more advantageously. The resistance values of the touch pads 10 tobe included in a group that performs the SP open operation at the sametime are preferably present within an error range.

The above-described embodiments has been described with respect to thecase of rows as an example, but the technical spirit of varying the opentime of the SP 10 a by the touch pads 10 is not limited to the row, butcan be applied to the case of columns or selecting the touch pad 10randomly.

On the other hand, the embodiment on the open time of the NSP 10 b or SP10 a of FIG. 42 or 43 has been described with respect to the case ofdetecting the touch signal in synchronization with the common voltage,but the open time of the NSP 10 b or SP 10 a can be determined insynchronization with a signal that is internally generated in the TDI 30or an externally given signal from the outside of the TDI 30, instead ofbeing synchronized with the common voltage in the case that the commonvoltage is not generated in the display device. The signals of the opentime or the close time of the NSP 10 b or SP 10 a that are given fromthe inside or outside of the TDI 30, may be a trigger signal or aninterrupt that is periodically generated by a timer or a counter.

The ON/OFF point in time of Vg for controlling the charging unit 12 insynchronization with the trigger signal or interrupt, is determined, andthe operating points in time of all the signals of FIG. 42 or 43 is alsodetermined in synchronization with the trigger signal or interrupt.

In the touch screen panel 50 according to the embodiment of FIG. 37, itis possible to detect a touch by scanning a group of the touch pads 10included in rows and a group of the touch pads 10 included in columns.

For example, if all of the touch pads 10 are scanned by rows, the touchpads 10 included in the row R1 are connected to a touch detectioncircuit from which all touch signals are detected at the same point intime. All the touch pads are sequentially scanned starting at R1 up toR7, and the touch signals for all the touch pads 10 included in the samegroup at each and every scan are detected.

Otherwise, if all of the touch pads 10 are scanned by columns, scanstarts at C1 and ends to C5 in the column direction. A touch is detectedat each and every scan by continuously repeating again a process ofstarting at C1 and ending to C5.

For example, assuming that touch pads are scanned in the row direction,all the touch pads 10 included in the row R1 perform the touch detectionoperations, when the touch pads of R1 are scanned, and all the touchpads 10 included in the rows R2 to R7 except for the row R1 may beconnected to the ground potential.

A touch detection operation is performed a plurality of times in the rowR1. Each time a touch is detected, the value is stored in a line memoryunit corresponding to R1. After undergoing filtering by using aplurality of pieces of data stored in the line memory unit, it isdetermined whether or nor a touch operation occurs, or a contact area iscalculated. After completion of the row R1, the same process is repeatedfor the row R2 as well. After completion of the row R7, ADC valuesextracted from the respective rows and touch data such as area valuesare stored in a frame memory unit. The CPU 40 or the signal processor 35calculates the touch areas or extracts the touch coordinates on thebasis of the data stored in the frame memory unit.

The touch coordinate can be defined as the center of gravity of an areathat is formed of an area or areas of one or a plurality of touch pads10, in which a touch unit such as a finger 25 is in opposition to one ora plurality of touch pads 10. Therefore, if a touch coordinate iscalculated by considering only the ADC value or the area extracted froma single touch pad 10, the center of the touch pad is extracted as thetouch coordinate. Since information about many locations is actuallypresent in the inside of the touch pad 10, it is impossible to extract aprecise position with only a single touch pad 10.

In order to detect a variety of locations within the touch pad 10, atouch coordinate is to be extracted by a combination of a plurality oftouch pads 10, that is, at least two or more touch pads 10. FIGS. 44Aand 44B are diagrams illustrating a method of extracting the touchcoordinate by a mutual combination or a relationship of the ADC value orthe calculated area detected in the touch pad 10, according to anembodiment of the present invention.

Referring to FIG. 44A, a finger 25 has a 50% share of an area in a touchpad 10 (“A”) and a touch pad 10 (“B”), respectively. The touch pads Aand B have the same area and it is assumed that an area value is 100(one hundred). The sum of the touch areas by the finger 25 is 100. Amongthe touch areas, the sharing ratios of the touch pads A and B are 50%,respectively. Therefore, it can be determined that the center of gravityis located at the center of the touch pads A and B.

In addition, referring to FIG. 44B, a sharing ratio of the area in thetouch pad 10 (“A”) by the finger 25 is 60%, and the sharing ratio of thearea of the touch pad 10 (“B”) is 40%. A total sharing ratio of theareas of the touch pads A and B is 100%, and the sharing ratio of thearea in the touch pad 10 (“A”) is 60%. Accordingly, the center ofgravity is located at a point of 40% from the left of the touch pad 10(“A”). This point become the touch coordinate. Thus, it is possible tolinearly calculate the touch coordinate depending upon a fine differencein the area by correlation of mutually adjacent touch pads 10.

In FIGS. 44A and 44B, a method of obtaining the touch coordinate for thefinger 25 that moves in the horizontal direction has been described asan example in the case of the touch pads 10 adjacent in the horizontaldirection, but it is possible to extract the touch coordinatetwo-dimensionally, in the case that the touch pads 10 are located in thehorizontal and vertical directions, and the finger 25 touches all thetouch pads 10 in the horizontal and vertical directions.

Since it is possible to extract an area in the present invention, thetouch coordinate is extracted as the area. Preferably, the touchcoordinate is calculated by correlation of the areas calculated in therespective touch pads 10.

Using the above-mentioned coordinate detection area configuration,according to an embodiment of the present invention a touch detectionmeans is a higher resolution than the resolution of the touch pad touchdetection is possible.

By a configuration of detecting the touch coordinate by using theabove-described area, a touch detection device according to anembodiment of the present invention, can perform touch detection withmuch higher resolution than that of the touch pads.

The TDI 30 used in the touch screen panel 50 of the present inventioncan be configured to detect the touch signal of the touch pads 10 of 100or 500, or more than 1000. Should touch signals are detected or sensedfrom one thousand of touch pads 10, one thousand of pins of the TDI 30are mapped with one thousand of touch pads 10 on a one-to-one mappingbasis. Otherwise, a multiplexer is provided in the outside of the TDIand one thousand of touch pads 10 are connected with the multiplexer.Thereafter, if the output of the multiplexer is set a small amount, thenumber of pins is reduced in the TDI but the separate multiplexer shouldbe added, to thus require an additional process and cause cost rises.

In order to manufacture the touch screen panel 50 that will be used in asmall-sized display device by using the TDI 30 that is capable ofdetecting the touch signal from one thousand of touch pads 10, only aportion of the touch detection function about a thousand of touch padsshould be used.

For this purpose, in an embodiment of a touch screen panel 50 configuredto have rows and columns as shown in FIGS. 37 and 46, a unit for settingan operating area of each of the touch pads 10 included in the row andcolumn directions is required.

For example, FIGS. 37 and 46 illustrate a touch screen panel 50 that isformed by 7×5 (row×column). If the number of the touch pads 10 is formedby 5×3 (row×column), only five groups of seven groups of touch pads 10should be selected in the row direction, and only three groups of fivegroups of touch pads 10 should be selected in the column direction.

A unit capable of selecting a group of touch pads in the row directionand a group of touch pads in the column direction is provided in theinside of the TDI, so as to perform a touch detection operation.Registers will be described as follows as an embodiment of the unit.

First, two types of registers such as a register for selecting a groupin the row direction and another register for selecting a group in thecolumn direction are required as the registers. In addition, two typesof registers are required as the register for selecting a group in therow direction, in which each of the two types of registers shouldinclude a unit for setting start and end points of the group thatperforms the touch detection. For example, it is assumed that there aretwo registers called REG1 and REG2 to set up a group in the rowdirection. If REG1 is a register to set a touch detection starting pointin the row direction, and REG2 is a register for determining an endpoint, an operation for the touch detection is performed from the row R3of FIG. 37 by the row R3 that is written in or selected from REG1, butR1 and R2 do not operate. In addition, an operation for the touchdetection is performed only until the row R7 by the row R7 that iswritten in or selected from REG2, but R8 or R9 that will be performedlater does not the touch detection operation. The same method as thecase of the row is applied to the case of the column, and it is possibleto select three groups in the column direction in various forms from C2to C4, or from C1 to C3, by two registers capable of setting start andend points.

The operation that detects a touch in only a portion of the touch padfrom the entire touch pads 10 that is capable of being detected by theTDI 30 may be performed in two types of methods.

According to the first method, only touch pads 10 required to operatethe touch detection connected to the touch detection circuit of FIG. 11,and the touch pads 10 excluded from the operation of the touch detectionare not connected to the touch detection circuit of FIG. 11.

According to the second method, all of the touch pads that are capableof being detected in the TDI 30 are connected to the touch detectioncircuit for detecting a touch, but data of a needed area is extractedfrom the memory unit in which the resulting value is included and isused for calculation of the touch coordinate.

Alternatively, these two methods are mutually combined to then be used.Referring to FIG. 37, for example, only R3 and R7 operate in the rowdirection, and R1 and R2 do not perform the touch detection. All of C1to C5 operate in the column direction and only data of C1 to C3 storedin the memory unit is used, but data of C4 and C5 is discarded.Otherwise, a touch is detected by using the touch detection circuit onlyin the columns of C1 to C3, but C4 and C5 do not detect a touch.Meanwhile, a touch is detected for every row of R1 to R7, but only areasof R3 to R7 are referred to from the memory unit in which the detecteddata is stored.

As mentioned earlier, the touch pad 10 is also used for the purpose ofdetecting a touch, but is also used for detection purpose of the commonvoltage.

A method of detecting a touch signal and a common voltage by touch pads10 according to an embodiment of the present invention will be describedas follows with reference to FIG. 45. Referring to FIG. 45, a group offifteen touch pads 10 in the row direction and a group of ten touch pads10 in the column direction exist, to thus configure a touch screen panel50 with one hundred fifty (150) of touch pads 10. A common voltage isused in a display device 200. In the case of the common voltagealternating in a line inversion manner, or the common voltage includingnoise, the reason why a touch signal should be detected in synchronismwith the common voltage, which will be the same as the above-describedreason.

In order to detect the common voltage, a unit for forming is needed asin FIG. 17 or 19. In the present invention, such a unit for formingCvcom is not separately provided but the touch pad 10 is used.

Referring to FIGS. 12 and 13, the touch capacitance Ct and the commonelectrode capacitance Cvcom are simultaneously formed in a single touchpad 10.

That is, when the finger 10 is located on the upper surface of a singletouch pad 10, a body 11 is grounded and the touch capacitor Ct whose oneside is connected to the point P of FIG. 11 and the common electrodecapacitor Cvcom whose one side is connected to the point P of FIG. 11and whose other side has a potential of the common electrode located onthe bottom of the touch capacitor Ct, are simultaneously formed. Thismeans that the common electrode capacitor Cvcom is formed in the touchpad 10, and means that the common voltage can be detected without usinga separate common voltage detecting unit.

Since the touch pad 10 can detect the touch and the common voltagesimultaneously, it is also possible to detect the touch signal and thecommon voltage in the touch detection circuit of FIG. 11 with a singletouch pad 10.

However, cross-talk can occur due to the timing difference of detectinga touch signal and the common voltage in a single circuit, and thedriving voltage Vdrv or the common voltage for detection of a touchsignal may cause distortion by the mutual influence.

Accordingly, it is preferable to separate the touch pad 10 for detectionof the touch and the touch pad 10 for detection of the common voltage.

Also, referring to FIG. 17 or 19, since it is preferable that Cdrv isnot used in order to improve the detection sensitivity of the commonvoltage, it is preferable to separate the touch detection circuitincluding Cdrv and the common voltage detection circuit having no Cdrv.

Referring to FIG. 45, there are the touch pads 10 for detection of thecommon voltage in three groups of the rows, which are R9, R12, and R15.In addition, one group has five touch pads 10 which are configured todetect the common voltage.

Only one of the fifteen touch pads 10 for detecting the common voltageis selectively used for detection of the common voltage. Therefore, amultiplexer or switching unit for connecting one of a plurality of touchpads 10 that are set for detecting the common voltage to the point P (apoint P in FIG. 17) of the common voltage detection circuit is needed.However, this is nothing but one embodiment according to FIG. 45 inwhich a plurality of the touch pads 10 and a plurality of the commonvoltage detection circuits corresponding to the plurality of the touchpads 10 may also be used.

In FIG. 45, if the touch detection areas are set to 10×5 (row×column),and thus the touch detection areas are set to R1 to R10 and C1 to C5,only the touch pads 10 for detecting the common voltage included in thetouch detection areas are used for detection of the common voltage. Inaddition, the touch pads 10 for detecting the common voltage other thanthe touch detection areas are not used as the common voltage detectionpurposes. Likewise, the touch pads 10 for detecting the common voltageare set in a plurality of rows and columns. Positions at which the touchpads 10 for detecting the common voltage are detected may vary dependingupon changes of the setting of the touch area of the TDI 30.

Assuming that the entire area in FIG. 45 is the touch detecting area,the common voltage should not be detected only in the touch pad 10included in one row and at least one should be present in the other row.

This is because, assuming that a touch pad 10 of R9 marked with “5”detects a common voltage first in an embodiment of scanning a touchsignal from R1 to R15, since the touch pad 10 of R9 marked with “5” thatis being used for detecting the common voltage does not detect thecommon voltage but has to detect the touch, when R8 has been scanned andthen R9 detects a touch, another touch pad should detect the commonvoltage. Since a touch pad for detecting a common voltage should not bepresent in R9, one touch pad should be selected from R12 or R15.Assuming that a touch pad 10 of R15 marked with “13” plays such a role,the touch pad 10 of R15 marked with “13” detects a common voltage at thetime of scanning R9, and the touch pad for detecting the common voltageshould be switched to another touch pad for detecting the common voltageof R9 or R12, before scanning R15 after having scanned R9.

As described above, according to a scan order for the touch detection, atouch pad for detecting a common voltage is changed and thus it ispossible to detect a common voltage in real-time by using the touch pad.

In the case that the touch pad 10 is an on-cell touch cell included in adisplay device shown in the embodiment of FIG. 13, the touch pad 10 maybe used as a back ground in a LCD display device of a transverseelectric field mode, as described above. In this case, the touch paddetects the common voltage continuously, to thus cause a malfunction ofthe image quality of the display device. That is, in the case that atouch pad 10 of R9 marked with “5” of FIG. 45 detects the common voltagecontinuously, and entrusts a function of detecting the common voltage toanother touch pad that is located in another row in only a sequence atwhich the touch pad 10 of R9 marked with “5” detects a touch, a timesharing ratio for common voltage detection of the touch pad 10 of R9marked with “5” becomes higher than that of another touch pad 10 forcommon voltage detection. In order to detect the common voltage in theembodiment of FIG. 18, since Vpre_com that is the charging voltage isapplied to the touch pad 10 for common voltage detection for aconsiderable period, this Vpre_com voltage generates an electric fieldwith respect to a voltage formed in a common electrode or a drainelectrode 255 of the LCD located on the bottom of the common voltagedetecting touch pad 10, to thereby cause the liquid crystal located onthe bottom of the common voltage detecting touch pad 10 to perform anoperation due to the electric field. In the case that the liquid crystalreacts with the electric field, the liquid crystal is changed into blackor gray as a whole, to thus cause a poor image quality.

For measures to solve this problem, the touch pads 10 for detecting thecommon voltage are used in rotation.

For example, assuming that the touch pad of R9 marked with “1” of FIG.45 is used when the first common voltage is detected, the touch pad ofR9 marked with “2” is used to detect the second common voltage. Then,the touch pad of R9 marked with “3” is used to detect the next commonvoltage. As such, the touch pads 10 for detecting the common voltageshould be used in rotation. The time width of the common voltage is 100μs at most, and the liquid crystal does not respond in an amount of timeof 100 μs or so. Accordingly, it is possible to solve the poor imagequality by the rotation of the common voltage detection touch pads. Sucha rotation is possible in a combination of the common voltage detectiontouch pads 10 included in same row, or even between the common voltagedetection touch pads 10 included in respectively different rows orcolumns.

Thus, in the case that the common electrode detecting touch pads 10operate in rotation, the row that is detecting the common voltagebecomes in a sequence at which the row detects a touch, to thus bechanged into a touch detection environment. For this, rotation of thecommon electrode detecting touch pads 10 included in a row is achievedin the common voltage detecting touch pads 10 included in another row.

So far, the embodiment of sequentially scanning the rows and detectingthe touches has been described, but a case of sequentially scanningcolumns and detecting touches can be equally achieved by using the samerotation technique.

Some mobile phones have function keypads enabling Return to Home ofMenu, and an operation such as Backward or Forward of Menu. Referring toFIG. 46 regarding the use of function keypads in a conventionalembodiment, a touch screen panel 50 applied to a cellular phone includestouch pads 10 and function keypads 20. These function keypads 20 may bemechanically driven, but recently in some cases the use of the functionkey using a touch increase.

FIG. 46 includes two function keypads that are provided in a regionwhere the touch pads 10 are mounted, beyond a A/A region of a displaydevice. The two function keypads named “Home Key” and “Back Key” areused in different places from the touch pads 10 that used for touchdetection, and thus require different functions from the touch pads 10.

FIG. 47 illustrates an implementation of the function keypads accordingto an embodiment of the present invention. Referring to FIG. 47, the TDI30 is divided into an input unit and an output unit. The input unit mayreceive a signal given from a flexible circuit substrate 96 such as COFor FPC (not shown), may give a signal to COF or FPC (not shown). Inaddition, the output unit of the TDI is a portion that is connected tothe touch screen panel 50, and that makes a signal transfer not possiblefor another region other than the touch screen panel 50.

Function keypads 20 are included in the output unit of the TDI 30, andare wired in the same manner as the touch pads 10, to thus pass throughthe upper surface of the A/A of the display device. The function keysignal wires 23 a to pass between the touch pads 10 are connected withthe function keypads 20 in the area of the touch screen panel 50 on theopposite side of the TDI 30. On the other hand, other function keysignal wires 23 b originate from the output unit of the TDI 30, do notpass through the A/A region of the display device, are wired with thetouch screen panel 50 on the opposite side of the TDI 30, through anon-visible region (or a bezel) of the display device (not shown), andare connected with the function keypads 20.

Further, the function keypads 20 may be connected with a protectiveglass pad, a protective plastic pad, or the like, that is not the touchscreen panel 50 through the input unit in the TDI 30. The functionkeypads perform only ON/OFF functions. Thus, when the touch pads 10 ofthe present invention are used as the function keypads, only a touch pad10 is used independently, to detect only an ON/OFF operation. Athreshold value (or a threshold voltage) for the ON/OFF detection may beused differently from a threshold value that is applied to the touch pad10.

It is desirable that the function keypads 20 also perform fac.cal andRTC identically to reduce a detection error. In the case that thefunction keypads do not exist on the upper surface of the displaydevice, the function keypads are not required to detect a touch signalin synchronization with the common voltage signal.

The function keypads 20 may be also used as the touch pads 10. A unitfor determining whether any of the touch pads 10 are used as touchdetection pads or function keypads is included in the inside of the TDI30. In the case of a 7×5 (row×col) structure as shown in FIG. 47, iffive function keypads are then absorbed into the touch pads of the rows,a touch screen panel 50 having a 8×5 (row×col) touch resolution isobtained. Such a function is changed by a register or a program includedin the TDI 30. Taking a method of modification by the register as anexample, a specific bit of the register is set as high or low, whichmakes a certain touch pad switched to the touch detection touch pad orthe function keypad. To this end, a specific area of the touch pad 10should be determined to allow these two functions in advance.

The function keypads as used herein, can also be used for the touch padsfor the touch detection, and thus can also be used for detecting alinear change in position of a touch unit such as a finger 25 inaddition to the function keypads that simply detect the ON/OFF. Thesefunction keypads are required for a scroll function, for example, thesefunction keypads are attached to one end of a phone and are used for thescrolling function such as pushing a finger up to increase the volume,and pushing the finger down to decrease the volume.

In order to linearly detect coordinates for the linear position changesof the finger 25, such a function cannot be performed by only a singlefunction keypad. As described above, a plurality of function keypadsshould be adjacent to each other, and the linear coordinate detectioncan be performed through a mutual relationship between the sharing areasof the plurality of function keypads or a mutual area reference. Such afunction does not differ from the case that the touch pad 10 detects atouch coordinate, but differs from only the case that a touch detectingposition is not located on the top surface of the A/A region of thedisplay device.

Accordingly, it is possible to use the touch pad according to thepresent invention for any purpose extracting the linear change in thecoordinates as a scroll wheel of the Apple iPod®.

Even when the touch pads 10 are used as the function keypads 20, thefunction keypads 20 preferably perform all of the features of theopening or closing operation of the NSP 10 b or the SP 10 a.

As described above, it may be assumed the function keypads 20 are someregions of the touch pads 10. As shown in FIG. 47, five function keypadscan be defined as the eighth row. Thus, since a touch screen panel 50with a resolution of 8×5 can be set, there is no constraint in functionsor time settings for the open and close of the NSP or SP. That is, whenthe first row of FIG. 47 operates as the touch pad 10, all of the touchpads 10 of the touch screen panel 50 including the function keypads 20are connected to the ground, or can follow the rules of the NSP open inthe present invention.

Further, at the moment the function keypads 20 detect the touch signal,it is possible to apply the technical idea regarding NSP open of thepresent invention to the remaining touch pads 10 except for the functionkeypads 20. In conclusion, timing about the NSP open or SP open of thefunction keypads 20 is not set separately, but is conducted insynchronization with the time about the NSP and SP open of the touchpads 10.

When the touch pads 10 of the present invention are used as the functionkeypads 20, threshold values to determine whether or not a touch occursshould be set separately, and threshold values for the ADC or the areacan be set identically or differently from each other.

This is because the function keypads 20 need sensitivity settingsseparately, since the function keypads 20 are designed to respond to adeep pressure on their purposes.

If the sensitivity of the function keypads is sensitive like normaltouch pads, the function keypads may react with even a momentary touch.As being the case, the function keypads do not need high sensitivity.Thus, it is preferable that threshold values to determine whether or nota touch occurs be separately set in the function keypads 20.

Threshold values may be set on the basis of the value of the ADC or thearea. Also, in order to perform the touch detection of the functionkeypads, it is also desirable to separately set a gain of FIG. 29. Thus,this is because the touch sensitivity can be adjusted by separatelysetting a gain of FIG. 29.

FIG. 48 is a table diagram showing settings of the register applied tothe function keypads according to an embodiment of the presentinvention. Referring to FIG. 48, the register is made of 4 bits and thuscan be set in sixteen (16) steps. Also, the threshold values have beenset on the basis of a ADC code. If address 00h of the register isselected, the threshold value becomes 50. In the case that the ADC codevalue detected due to the touch by the function keypads 20 is 50 ormore, it is recognized as a touch. If address 09h is selected, only inthe case that the ADC code value detected due to the touch by thefunction keypads 20 is 500 or more, it is recognized as a touch. Thus,by properly adjusting the threshold value, it is possible to adjust thetouch sensitivity in the function keypads 20. Such a method can beapplied to the touch detection of the touch pads 10 identically.

On the other hand, suppose an application example that the finger 25completely covers the function keypad, and thus a touch is detected buttouch sensitivity should be low. In this case, as shown in the equationof FIG. 29, it can be solved by lowering a gain or adjusting a thresholdvalue on the touch detection. Otherwise, the sensitivity of the functionkeypad may be adjusted by the shape of the function keypad.

By the above-described configuration, according to an embodiment of thepresent invention, an input method that uses the function keypads havingthe same structure as the touch pads but differing from that of thetouch pads can be provided to users, by adjusting the touch detectionthreshold values and the amplifier gains of the function keypads.

FIG. 49 is a diagram showing a method of adjusting the sensitivity withthe shape of the function keypads according an embodiment of the presentinvention. Referring to FIG. 49, a touch detection pattern in the insideof the function keypads 20 is formed of a net or mesh structure. An areasharing ratio of the touch detection pattern is determined depending onthe width of the pattern. An example of the net or mesh structure hasbeen described with reference to FIG. 49, but the touch detectionpattern is not limited to the shape. However, the touch detectionpattern may occupy a portion of the pattern of the function keypads ormay cover the whole shape of the function keypads. According to theadvantage of such a pattern, even if the gain or the threshold value isset high, it is possible to perform the touch detection only when thetouch unit contacts the function keypads 20 as widely as possible.Accordingly, an operation by an unwanted touch that may occur when thetouch unit contacts a part of the function keypads 20 unconsciously canbe prevented.

By the above-described configuration, according to an embodiment of thepresent invention, the structure of the touch pad 10 is partiallymodified, and thus an input function as the function keypads differentfrom the touch pads can be provided for users.

In order to extract the touch coordinate from the touch pads 10, it isnecessary to make a correlation rule with the neighboring touch pads 10.According to the correlation rule, when the finger 25 touches aplurality of touch pads 10, an area of the finger 25 between the finger25 and the plurality of touch pads 10 contacting the finger 25, and thecenter of gravity of the area formed by the plurality of touch pads 10are obtained. The obtained point becomes a touch coordinate. However,since there is no neighboring touch pads 10 in the edge portion of thetouch screen panel 50 that is the last part of the touch pads 10, it isnot easy to obtain the center of gravity completely.

FIG. 50 is a diagram showing a conventional configuration of an edgepart of a touch screen panel 50. Referring to FIG. 50, touch pads 10 arelocated in the A/A of a conventional display device. The reason is thatas described above, the conventional detection method has a wide leftand right bezel width due to the touch screen panel 50, and thus aconfiguration of the touch pads 10 exceeding the A/A of the displaydevice further widens the left and right bezel width due to the touchscreen panel 50, to thereby cause poorer marketability. Due to this,since there are not the touch pads 10 attached to the edge portions ofthe touch pads 10, blind zones for detection may occur.

FIG. 51 is a diagram illustrating a configuration of an edge portion ofa touch screen panel according to an exemplary embodiment of the presentinvention, to solve these problems.

In the case of the touch screen panel 50 of the present invention, sincesensor signal wires 22 are disposed between the touch pads 10, that is,in the A/A on the screen of the display device, the sensor signal wires22 that are wired on the left and right bezel of the touch screen panel50 are minimized.

Thus, even though the touch pads 50 are mounted in excess of the A/A ofthe display screen, an increase in the width of the bezel of the touchscreen panel 50 is not induced. If the touch pads 50 are extensivelymounted in the outside of the A/A of the display device as shown in FIG.51, the blind zones for detection are pushed out of the A/A of thedisplay device, and thus no blind zones occur in the A/A.

According to the present invention, a touch coordinates is recognizedand a contact area is recognized between the touch unit such as thefinger and the touch pads 10. Referring to FIG. 14, according to thepresent invention, since an opposite area of the touch pads 10 withrespect to the finger 25 can be calculated, a total area of the finger25 contacting the touch screen panel 50 is calculated by summing all thecontacting areas of the plurality of touch pads 10. In addition, it ispossible to obtain the touch coordinate by obtaining the center ofgravity of the area. Thus, the touch coordinate is displayed on thetwo-dimensional x-axis and y-axis and the area information is thendisplayed together with the touch coordinate, which enables the touch tobe displayed three-dimensionally.

When an area change rate per hour of the finger 25 contacting the touchscreen panel 50 is calculated, it is also possible to detect a force orpressure applied by the finger 25. In order to perform these operations,according to the present invention, when the touch coordinates are sentto a CPU of a set, the time information and the area information aretransmitted together. The CPU of the set computes the force or pressureof the touch unit on the basis of the time information and the areainformation. Otherwise, the CPU 40 and a signal processor 35 in theinside of the TDI calculates the force or pressure applied by the touchunit, and transfers the calculated result to the CPU of the set.

Such area detection can be used for a variety of uses. For example, inthe case of writing letters, the letters become thicker or narrower inproportion to an area of a writing instrument contacting the touchscreen panel 50. When a conductive brush is used to draw a picture, itis possible to draw the same picture as an actual object. In addition,some applications may perform a multi-layer command. In order to operatean MP3 player in a mobile phone, the following two layer command stepsare generally used: 1) a first step of selecting a MP3 player among anumber of applications; and 2) a second step of touching play buttons tohear music songs. In this case, according to a multi-layer structurecommand of the present invention using the area, if the MP3 player isslightly tapped, the contact area is smaller and the player is selected,and if the MP3 player is strongly tapped, the contact area is wider, andthe player is selected and played. Otherwise, in the case of keyboardapplications, the size of the sound may vary differently depending onthe intensity of hitting the keyboard.

On the other hand, a plurality of the TDIs 30 may be used in a singletouch screen panel 50. In the case that the touch screen panel 50 iswide, the touch pads 10 are placed on the touch screen panel 50 with asignal TDI 30, and thus the area of the touch pad 10 is widened.Accordingly, detection resolution for detecting the touch coordinate maydecrease. As a result, it is preferable that a plurality of TDIs 30should be used to get a small area of the touch pads 10.

In order to use a touch screen panel 50 with a plurality of TDIs 30, thetouch pads 10 formed on the touch screen panel 50 includes the touchpads 10 in the row direction and the touch pads 10 in the columndirection that are formed in the same line or with the same thickness.

FIG. 52 is a diagram illustrating a plurality of TDIs 30 used in anembodiment of the present invention. Referring to FIG. 52, a pluralityof TDIs 30 are used in a touch screen panel 50 in which and the touchpads 10 are patterned in an identical interval. Communication cables andsignal wires 29 are present between a plurality of TDIs 30 so thatcommunications and necessary signals are transmitted between the TDIs. Aplurality of signal wires are used as the communication cables andsignal wires 29. These are I2C or SPI signal wires or a USB signal wiresfor serial communications which are a plurality of synchronizationsignals to be described later. A master function is assigned to one ofthe plurality of TDIs 30, and a slave function is assigned to the otherof the plurality of TDIs 30. A unit for designating the master functionand the slave function is included in the inside of the TDI.

The TDI 30 that is used as a master sends control signals to the TDI 30that is used as a slave through the communication cables and signalwires 29, and controls the slave function. Further, although not shown,the CPU 40 other than the TDI 30 is present separately from the TDI 30and controls a plurality of TDIs 30 via the communication cables andsignal wires 29. In this case, each of TDIs 30 is assigned with an ID(Identification) to discriminate one of the TDIs 30 from the others. TheTDI 30 has a hardware pin or software configuration for setting the ID.Taking the hardware configuration as an example, a plurality of ID pinsare connected to a high or low signal.

With this configuration, in order to prevent malfunctions due to contactof a conductive body such as droplets, the touch pads 10 which arecontrolled by the two TDIs 30 in the touch screen panel 50 shouldoperate as if they are controlled by a single TDI 30. For example,assuming that the row is scanned, in the case of starting scanning fromR1, and ending scanning to R7 via R2 and R3, the master TDI 30 or theexternal CPU sends a frame sync signal via the signal wires orcommunication cables 24. R1 on the left side of FIG. 52 and R1 on theright side of FIG. 52 start scanning at an identical point in time bythe frame synchronizing signal. After the completion of a scan of R1,the master TDI or the external CPU gives a prompting signal to startscanning of R2. In synchronism with the prompting signal, a scan of R2is simultaneously carried out. Likewise, since a scan start point intime of a frame and a scan start point in time of each row aresynchronized by a signal applied by the master TDI or the external CPU,scanning may appear to operate by a single TDI. Thus, malfunction due toa conductive material such as water droplets is prevented. In addition,since opening of the NSP or the SP operates in synchronism with aplurality of TDIs 30, it is possible to implement in the same manner asa single TDI 30.

As described above, when a plurality of TDIs are activated on amaster-slave basis, and the scan and the pad opening are synchronized,it is possible to provide a touch screen function of a big screen.

Meanwhile, in the case of actually using the touch screen panel 50 inthe present invention, the electrostatic discharge (ESD) is oftenintroduced into the electrostatic touch pads 10. If the ESD is appliedto the touch pad 10, the potential of the point P in FIG. 11 may bechanged, and thus a case of recognizing the potential changes as a touchwrongly may occur.

Referring to FIGS. 12 and 13, the touch pads 10 according to the presentinvention are located on the bottom of a protective layer 24 such asglass. Therefore, the static electricity may be applied to theprotective layer 24 and may be introduced into a joint between theprotective layer 24 and the touch pads 10. Thus, in the configuration ofFIGS. 12 and 13, the static electricity may be introduced from the edgeportion of the touch screen panel 50. Accordingly, if a unit forabsorbing static electricity is provided in the edge portion of thetouch screen panel 50, the static electricity will not penetrate intothe interior of the touch screen panel 50.

FIG. 53 is a diagram illustrating a configuration for discharging thestatic electricity according to an exemplary embodiment of the presentinvention. Referring to FIG. 53, ESD absorption wires 27 are provided inthe outer parts of the touch screen panel 50. The ESD absorption wires27 are connected to the ground or a DC voltage source having a constantpotential on a flexible circuit substrate 96 such as COF or FPC, orconnected to the TDI 30 so as to be connected to the ground or a DCvoltage source having a predetermined level in the TDI. In addition, itis not desirable that the ESD absorption wires 27 forms a closed-loop.This is because call reception sensitivity of cell phones can beaffected by effect of the antenna. Thus, the ESD absorption wires 27originate from at least two points and are not interconnected. Inaddition, in order to minimize the ESD path as shown in the circularportion of FIG. 53, it is preferable that the ESD absorption wiresoverlap in the closest distance.

Since the ESD absorption wires 27 are connected to GND or apredetermined DC level, ESD introduced from the edge portion of thetouch screen panel 50 is absorbed by the ESD absorption wires 27, anddischarged to the outside of the touch screen panel so that the touchpads 10 are securely protected by ESD.

FIGS. 54 and 55 are a cross-sectional view and an exploded perspectiveview of a display device with a built-in touch-screen panel,respectively. Referring to FIGS. 54 and 55, the touch screen panel andthe display device with the built-in touch-screen panel according to thepresent invention will be described below.

As shown in FIG. 54, a touch screen panel according to the presentinvention may be patterned on the upper surface of a color filter 215 ofa display device 200. A touch-screen panel according to the presentinvention may be patterned on the bottom surface of a TFT substrate, butsuch a relevant description has been omitted in the specification. Acommon electrode 220 is formed on the lower surface of the color filter215 of a conventional LCD display device. As another example, in atransverse electric field mode such as that of FIG. 34, the commonelectrode 220 is formed on the TFT substrate 205. In the example of FIG.34 or 54, as shown, the touch pads 10 are patterned on the upper surfaceof the color filter 215.

A patterning process may be performed in a process of manufacturing acolor filter 215, or performed after the TFT substrate 205 and the colorfilter substrate 215 have been incorporated with each other. Recently,in order to reduce the thickness of the display device, a slimingprocess is in progress often for the purpose of reducing the thicknessafter combining the two substrates. Accordingly, the patterning processof the touch pads 10 should proceed after completion of the slimmingprocess, so that the touch pads 10 are not lost.

Meanwhile, a protective panel 52 such as reinforced glass may be mountedon the upper surface of the touch pads 10, in order to protect the touchpads 10. In the embodiment of FIG. 54, the protective panel 52 isattached on the upper surface of the color filter 215 by means of atransparent adhesive material such as a UV-curable resin 98, or attachedto the upper surface of the edge portion of the protective panel by DAT(Double Adhesive Tape).

The touch screen panel formed in the display device such as LCDaccording to the present invention detects a common voltage and detectsa touch signal in synchronism with the common voltage, in the case thatthe display device operates by the alternating common voltage in thesame manner as the line inversion driving method of the LCD. Inaddition, in the case of the transverse electric field mode or the dotinversion driving method, driving noise may be generated in the liquidcrystal driving process. When the driving noise affects the touchsignal, it is preferable to detect the driving noise and detect thetouch signal in synchronization with the detected driving noise.

Although it has not been shown in FIG. 54 or 55, a polarizing plate isattached to the upper surface of the touch pads 10 according to thepresent invention.

In the illustrated example, a drive IC 60 for displaying images on a LCDis mounted in the form of a COG pattern on the TFT substrate 205. A TDI30 that is a touch drive IC for controlling a touch signal is mounted inthe form of a COG or COF pattern on the color filter 215. FPCs 96 and 97such as FPC or COF are withdrawn from the drive ICs 30 and 60,respectively. Further, the touch drive IC 30 and the LCD drive IC 60 maybe integrated into a single IC, in the embodiment of FIG. 55.

Meanwhile, according to the present invention, a plurality of touchescan be detected. Referring to FIG. 25, the touch pads 10 according tothe present invention have an independent coordinates at eachindependent location. Accordingly, each touch pad 10 can detect aplurality of touch signals for the plurality of touch inputs. Assumingthat a palm (not shown) covers thirty-five (35) touch pads 10 on theupper surfaces of the 35 touch pads 10 shown in FIG. 25, it is possibleto detect that the 35 touch pads 10 have been touched.

In the case that the area of the touch pad of the present invention 10is small, the touch unit such as the finger 25 opposite to the touchpads 10, will face typically a plurality of touch pads 10. Therefore,since a plurality of touch pads 10 are in contact with a touch unit, itis necessary to detect a single coordinate from a group consisting of aplurality of touch pads 10. The touch coordinate becomes the center ofgravity of the group that has been touched.

FIG. 56 is a diagram illustrating a configuration of determining a touchgroup according to an embodiment of the present invention. Referring toFIG. 56, a “finger A” of FIG. 56 has touched ten (10) touch pads 10, inwhich relative values of the areas extracted due to the touch of thefinger are marked on the respective touch pads 10. The next area to theareas marked with “9” and “7” along the second row of the ten (10) touchpads 10 becomes an area of zero (0). Thus, it can be seen that a touchhas occurred only until the touch pad marked with “7” and the subsequenttouch pads are not touched. A boundary portion of the touch becomesbetween the touch pads 10 marked with “7” and “0.”

Thus, when a touch occurs, a touch area is extracted and when a touchdoes not occur, a touch area is not detected. It is possible to identifythe boundary portion between a case when a touch occurs and another casewhen a touch does not occur. It is possible to distinguish regions wherea touch has occurred by a finger from the other regions by a combinationof the boundary portions. Through a process of grouping the areas of thetouch pads 10 included in the touch regions as a group where a touch hasoccurred by a finger, a plurality of touch pads 10 can be recognized asif it were a touch pad. The center of gravity of a group becomes a touchcoordinate of the group.

In FIG. 56, a “finger B” group is a separate group and does not have amutual interconnection with the “finger A” group. Through grouping ofthe “finger B” group, it is possible to extract a touch coordinate thatis the center of gravity of the “finger B” group. It is also possible toextract touch coordinates the “finger A” group and the “finger B” group.Thus, the present invention enables multi touch detection that detects aplurality of touches.

As described above, a display device with a built-in touch screen panelaccording to the present invention has advantages that has a simpleprocess, an improved yield, a thin thickness, and an enhancedtransmittance, with no films, in comparison with the conventional casethat touch pads 10 are formed on film or glass and then the film orglass is attached on a display device. In addition, when an LCD processsuitable for mass production is used, and then a touch screen panelaccording to the present invention is fabricated on the upper surface ofan LCD, it is possible to produce products at a low manufacturing costand high yield.

However, the present invention is not limited to the above embodiments,and it is possible for one who has an ordinary skill in the art to makevarious substitutions, modifications and variations without departingoff the spirit of the invention defined by the claims.

[Description of reference numerals] 10: touch pads 10a: sensing pads(SP) 10b: non-sensing pad (NSP) 11: space filler portion 12: chargingunit 12-1: output unit of charging unit 12-2: input unit of chargingunit 14: touch detector 15: common voltage detector 16: switching unit18: amplifier 18a: differential amplifier 19: comparator 20: functionkeypads 22: sensor signal wires 23: function keypad signal wires 25:finger 26: conductor 27: ESD absorption wires 29: communication cablesand signal wires 30: touch drive IC 31: driver 33: timing controller 35:signal processor 40: CPU 46: communication unit 47: power supply 50:touch screen panel 52: protective panel 57: adhesive material 58: airgap or contact member 59: connectors 60: drive ICs 90: active region 92:invisible region 96: FPC 98: UV-curing resin 200: display device 205:TFT substrate 210: liquid crystal layer 215: color filter 217:background 220: common electrode 230: sealants 242: gate lines 244: datalines 246: common electrode lines 248: pixel electrode lines 250: TFT251: gate electrode 253: source electrode 255: drain electrode 257:semiconductor layer 270: dots

The invention claimed is:
 1. A touch detection apparatus installed in adisplay device to sense a generation of touch capacitance Ct byapproaching a touch input device of a finger of a human body or aconductor similar to the finger to the display device, the touchdetection apparatus comprising: a touch pad configured to form the touchcapacitance Ct between the touch pad and the touch input device; adriving capacitor Cdrv, wherein one portion of the driving capacitorCdrv is connected to the touch pad and the other portion of the drivingcapacitor Cdrv is applied with a driving voltage for touch detection; atouch detector configured to be connected to the touch pad and detect atouch signal using a driving back phenomenon when the touch capacitanceCt is added to the driving capacitor Cdrv depending on whether the touchinput device is touched; and a common voltage detector configured todetect a common voltage generated from the display device, wherein whenthe common voltage is not detected by the common voltage detector or avalue detected by the common voltage detector has an error, commonvoltage synchronization is performed using common voltage informationwhich is pre-stored during a factory calibration process, the commonvoltage information comprising the duration of a high section of thecommon voltage, the duration of a low section of the common voltage or arising edge of the common voltage, the common voltage synchronizationcomprising adjusting the duration of the high section of the commonvoltage, adjusting the duration of the low section of the commonvoltage, or adjusting the rising edge of the common voltage.
 2. Thetouch detection apparatus of claim 1, further comprising: a memory unitconfigured to store the touch signal detected by the touch detector; anda driving voltage generator configured to generate the driving voltagein synchronization with the common voltage.
 3. The touch detectionapparatus of claim 2, wherein the driving voltage is applied to oneportion of the driving capacitor Cdrv in synchronization with any one ofthe common voltage or the charging period of the charging device.
 4. Thetouch detection apparatus of claim 1, wherein when the common voltage isnot detected, a CPU or a signal processor of a touch drive IC extracts aduration of a non-detected common voltage among common voltage elementsstored in a memory and detects the touch signal in synchronization withthe extracted duration.
 5. The touch detection apparatus of claim 4,wherein the common voltage element is at least any one of a duration ofa HIGH period or a duration of a LOW period of the common voltage oreach duration of the HIGH and LOW periods of the common voltage in aback porch and a front porch of an image frame.
 6. The touch detectionapparatus of claim 1, wherein when the detected common voltage has anerror, a predetermined window is set based on a duration value of thecommon voltage stored in a memory and when the common voltage is notdetected for a time to which the window is added in the duration whichis a reference, a CPU generates a virtual common voltage as a signalrequired for synchronization.
 7. The touch detection apparatus of claim1, wherein an oscillator is used to generate the common voltage and whena period of the oscillator is changed depending on a change intemperature, a common voltage elements having the changed perioddetected in real time are stored in a memory and are used for detectingan error.
 8. The touch detection apparatus of claim 7, furthercomprising: a determination device configured to select any one of theelements detected in the factory calibration and the elements detectedin the real time calibration and use the selected element for the commonvoltage synchronization.
 9. The touch detection apparatus of claim 1,further comprising a common electrode capacitance Cvcom, wherein thecommon electrode capacitance Cvcom is formed between the touch pad and acommon electrode of the display device.
 10. The touch detectionapparatus of claim 1, wherein the driving capacitor Cdrv is notconnected to the common voltage detector.
 11. The touch detectionapparatus of claim 1, wherein the touch pad is connected to the touchdetector or the common voltage detector.
 12. The touch detectionapparatus of claim 1, further comprising a charging device for applyinga precharge voltage, wherein the charging device is connected to thetouch pad which is connected to the common voltage detector.
 13. Thetouch detection apparatus of claim 12, wherein the charging device is aswitching device and an output unit of the switching device which isconnected to the touch pad connected to the common voltage detector isin a high impedance state at the time of detecting the common voltage.14. The touch detection apparatus of claim 12, wherein the chargingdevice maintains an off state for a predetermined period and the commonvoltage detector detects the common voltage in the state in which thecharging device is in the off state.
 15. The touch detection apparatusof claim 12, wherein the charging device is turned on/off insynchronization with the common voltage.
 16. The touch detectionapparatus of claim 12, further comprising: a device configured to set acharging period of the charging device.
 17. The touch detectionapparatus of claim 1, wherein the touch detector detects the touchsignal when a predetermined period lapses after the driving voltage isapplied.
 18. The touch detection apparatus of claim 1, wherein an inputunit of the common voltage detector is in a high impedance state. 19.The touch detection apparatus of claim 1, wherein a signal output fromthe common voltage detector is input to a comparator to detect whetherthe common voltage is in a HIGH state or a LOW state.
 20. The touchdetection apparatus of claim 19, wherein at least one of an upperreference voltage for detecting the HIGH state of the common voltage anda lower reference voltage for detecting the LOW state of the commonvoltage is input to the comparator.
 21. The touch detection apparatus ofclaim 1, wherein at least one of touch pads is sequentially connected tothe common voltage detector.
 22. The touch detection apparatus of claim1, wherein when the touch pad connected to the common voltage detectoris connected to the touch detector, other touch pads which are notconnected to the touch detector are connected to the common voltagedetector to detect the common voltage.
 23. The touch detection apparatusof claim 1, further comprising: a device configured to output a signalof the common voltage detector to an external component separated fromthe touch drive IC (TDI).
 24. The touch detection apparatus of claim 23,further comprising: a device configured to determine whether to outputthe signal of the common voltage detector to the external component. 25.The touch detection apparatus of claim 1, wherein a voltage detected bythe touch detector at the non-touch time is determined by the following<Equation 1>, when the touch capacitance Ct is added, the voltagedetected by the touch detector is determined by the following <Equation2>, and the driving back is generated by a difference between the<Equation 1> and the <Equation 2>, $\begin{matrix}{\mspace{20mu}{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{Vh} - {Vl}} \right)\;\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp}}}}}} & \left\langle {{Equation}\mspace{14mu} 1} \right\rangle \\{{{\Delta\;{Vsensor}} = {{Vpre} \pm {\left( {{Vh} - {Vl}} \right)\;\frac{Cdrv}{{Cdrv} + {Cvcom} + {Cp} + {Ct}}}}},} & \left\langle {{Equation}\mspace{14mu} 2} \right\rangle\end{matrix}$ wherein, in the Equation 1 and Equation 2, ΔVsensorrepresents the voltage detected by the touch detector, Vh represents aHIGH level voltage applied to the driving capacitor, Vl represents a LOWlevel voltage applied to the driving capacitor, Cdrv represents adriving capacitance of the display device, Cvcom represents a commonelectrode capacitance of the display device, Cp represents a parasiticcapacitance of the display device, and Ct represents the touchcapacitance.
 26. The touch detection apparatus of claim 25, wherein thetouch detector detects a touch area of the touch input device for thetouch pad in response to a size of the driving back.
 27. The touchdetection apparatus of claim 1, wherein a sensor signal line ispositioned at left and right sides of the touch pad.
 28. The touchdetection apparatus of claim 1, wherein the rest touch pads which do notperform touch detection are in a floating state.
 29. The touch detectionapparatus of claim 28, wherein the touch pads which do not perform thetouch detection are entered into the floating state before a chargingdevice of the touch detector is turned on.
 30. The touch detectionapparatus of claim 1, wherein after the driving voltage is applied tothe driving capacitor Cdrv connected to the touch detector, the touchpad connected to the touch detector is separated from the touchdetector.
 31. The touch detection apparatus of claim 30, wherein thetime when the touch pad connected to the touch detector is separatedfrom the touch detector is in 1 ns to 100 μs after the driving voltageis applied to the driving capacitor connected to the touch detector. 32.The touch detection apparatus of claim 30, wherein the touch padseparated from the touch detector is re-connected to the touch detectoror applied with a predetermined voltage after the touch detection of thetouch detector is completed.
 33. The touch detection apparatus of claim32, wherein the predetermined voltage is a ground (GND) voltage or a DCvoltage having a predetermined size.
 34. The touch detection apparatusof claim 1, wherein after a touch detection operation of the touchdetector is completed, a non-detection touch pad which does not performtouch detection in a floating state is applied with a ground voltage ora DC voltage having a predetermined size.